isiolo international airport engineering design report

Isiolo Airport: Comprehensive Pavement Design Engineering Report

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REVISE COVER PAGE

INSERT MOTR Logo

Government of the Republic of Kenya Kenya Airports Authority (KAA)

Kenya

Airport Pavement Design Report Engineering Design Report No:

ISAT 0211/02

Reconstruction of Pavement Structures at Isiolo Airport in Isiolo, Kenya

Kensetsu Kaihatsu Ltd February 2011

Reconstruction of Pavement Structures for Isiolo Airport, Isiolo - Kenya |2011

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CONFIDENTIALITY AND © COPYRIGHT

This document is for the sole use of the addressee (Kenya Airports Authority (KAA), Government of

the Republic of Kenya) and Kensetsu Kaihatsu Limited. The document contains proprietary and

confidential information that shall not be reproduced in any manner or disclosed to or discussed with

any other parties without the express written permission of Kensetsu Kaihatsu Limited. Information

in this document is to be considered the intellectual property of Kensetsu Kaihatsu Limited in

accordance with Kenyan copyright law. This report was prepared by Kensetsu Kaihatsu Limited for

the account of Kenya Airports Authority (KAA). The material in it reflects Kensetsu Kaihatsu Limited’s

best judgement, in the light of the information available to it, at the time of preparation. Any use

which a third party makes of this report, or any reliance on or decisions to be made based on it, are

the responsibility of such third parties. Kensetsu Kaihatsu Limited accepts no responsibility for

damages, if any, suffered by any third party as a result of decisions made or actions based on this

report.

©2011 Kensetsu Kaihatsu Limited


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FORMAT OF REPORT

COPYRIGHTS

EXECUTIVE SUMMARY

TABLE OF CONTENTS

LIST OF TABLES

LIST OF FIGURES

LIST OF EQUATIONS

NOTATIONS, SYMBOLS AND TERMS

TABLE OF CONTENTS

CHAPTER 1

1. INTRODUCTION

1.1 Background

1.1.1 Status of the site

1.1.2 Works under Construction

1.2 Justification of the project 1.2.1 Necessity of rehabilitation of the airport 1.2.2 Scope of Study and Works 1.2.3 Isiolo Airport Project and Surrounding Areas 1.2.4 Geophysical Details of Isiolo Airport in Isiolo Eastern Province region of Kenya

1.3 Brief Background of Project Area

1.3.1 Climate and Vegetation

1.3.2 General Topographic, Geographic and Existing Conditions

1.4 Relevant Documents and Records

CHAPTER 2

2. BASIC SAMPLING AND SURVEY PROCEDURES IN BRIEF

2.1 Preliminary Field Survey

2.2 Basic Sampling Regime

2.3 Geological and Soil Survey in General

2.4 Groundwater Survey in General

2.5 Ground Movement Survey in General


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CHAPTER 3

3. TESTING AND INVESTIGATION REGIMES ADOPTED

3.1 Design Criteria of Testing, Investigation and Analytical Regimes

3.1.1 Preamble

3.1.2 Postulated Failure Mechanism of Pavement and Subgrade Layers

3.2 In-situ and Laboratory Testing

3.2.1 Determination of Basic In-situ Material Properties

3.2.2 Brief Introduction of In-situ and Laboratory Tests Undertaken

3.3 Summary of Laboratory Methods of Testing

3.3.1 Specific Gravity

3.3.2 Atterberg Limits

3.3.3 Sieve Analysis

3.3.4 Natural Moisture Content

3.3.5 Dry and Bulk Density

3.3.6 Aggregate Tests

3.3.7 Compaction Characteristics

3.3.8 Compressive Strength (UCS) and Bearing Capacity (CBR)

3.3.9 Durability

3.4 Summary of In-situ Methods of Testing

3.5 Schedule and Summary of Tests Performed

3.5.1 Laboratory Tests

3.5.2 In-situ Tests

3.6 Proposal for Performance-based specification for geogrids

3.7 Proposed Post-Construction Tests

3.7.1 Deflection Tests

3.7.2 Core Sampling and Testing

CHAPTER 4

4. RELEVANT ENGINEERING CONCEPTS AND THEORIES APPLIED

4.1 Outline of Methodology of Data Analysis, Evaluation and Criteria for Suitability

4.2 Determination of Basic Parameters

4.2.1 Standard Soil Model Expressions

4.2.2 Concepts Applied for Analyzing Impact of Environmental Factors

Effect of Swelling

Effect of Variation In Design Moisture Content


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Seasonal Effects On Bearing Capacity and Resilient Modulus

4.3 Bearing Capacity Analysis

4.3.1 Derivation of correlation of N-value, UCS and CBR

4.3.2 Derivation of CBR and qu Relations for Stiff Geomaterials

4.4 Consolidation and Settlement Related Analysis

4.4.1 Estimation of Consolidation and Shear Stress Paths

4.4.2 Analyzing Construction History for Settlement Prediction

4.5 Shearing Strength and Critical State Analysis

4.5.1 Analysis of a Soil Element along the Slip Failure Plane

4.5.2 Application of Modified Critical State Soil Mechanics

4.6 Deformation Resistance Analysis

4.6.1 Application of Deformation Concepts

4.6.2 Determination of Modulus of Deformation Parameters

4.6.3 Computation of Linear Elastic Range

4.7 Geophysical Survey Analysis

4.8 Concepts Applied for OPMC Stabilization

4.8.1 Theoretical Considerations

4.8.2 Proposed Method of Determining Optimum Batching Ratio (OBR)

4.9 Concepts of Cementation on Soil Particle Agglomeration

CHAPTER 5

5. MATERIALS CHARACTERIZATION AND ANALYSIS OF TEST RESULTS

5.1 Basic Physical and Mechanical Parameters

5.2 Correlation between Physical, Mechanical and Strength Parameters

5.3 Development of Test Regimes

5.4 Dynamic Cone Penetration (DCP) Test Results

5.5 Aggregate Test Results

5.6 Summary of Bearing capacity and shearing strength parameters

5.7 Bearing Capacity Test Results

5.8 Consolidation Test Results

5.9 Shearing strength Test Results

5.10 Modulus of Deformation, Elastic Modulus and Linear Elastic range

5.11 Deformation Properties and Linear Elastic Range

5.12 Summary of Effects of Curing Periods


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CHAPTER 6

5 APPLICATION OF TEST RESULTS


6.2 Correlation of Physical, Mechanical and Strength Parameters

6.3 Dynamic Penetration Test Results


6.5 Laboratory Test Results



6.8 Shearing Strength Test Results

6.7.1 Application of Principle Stresses within the Soil Elements

6.7.2 Shearing Strength Test Results

6.9 Modulus of Deformation and Elastic Modulus Test Results


6.11 Durability Test Results

CHAPTER 7

7. PAVEMENT STRUCTURAL DESIGN

7.1 Scope

7.2 Fundamental Design Philosophy

7.3 Comparison of Design Data with Various Design Criteria 7.3.1 Comparison of Design Criteria for Physical, Strength and Bearing Capacity Parameters

7.3.2 Comparison of Applicable Specification Criteria for Stabilized Natural Gravel and Design

Parameters

7.3.3 Comparison of Modulus of Deformation Parameters

7.3.4 Comparison of Durability Parameters

7.3.5 Comparison of Tested Material Properties and Specified Requirements

7.3.6 Conclusions Regarding Design Parameters

7.3.7 Adopted Design Criteria

7.4 Evaluation of Air Traffic Volume and Growth

7.5 Engineering Analysis of Geomaterial Properties

7.6 Evaluation of Strength of Existing Subgrade

7.6.1 Relatively Stable Geomaterials

7.6.2 Analysis of Problematic and/or Expansive Soils


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7.7 Determination of Pavement Structural Design

7.7.1 Determination of Total Pavement Thickness Required

7.8 Comparison of Various Adequate Designs

CHAPTER 8

8. ANALYSIS OF TIME DEPENDENT STRUCTURAL SOUNDNESS 8.1 Analysis of Structural Capacity Deterioration with Time Progression based on the SCDR Model

8.1.1 Definition of Structural Failures 8.1.2 Fundamental Theories/Concepts Applied in Developing SCDR Model

(1) Theories and/or Concepts Considered 8.1.3 Analysis of Structural Capacity

1) Initial Structural Capacity 2) Deterioration of Structural Capacity with Time Progression

3) Analysis of Influence of Environmental Factors 8.2 Analysis of Time Dependent Structural Capacity for Varying Designs of Isiolo Airport

CHAPTER 9

9. METHOD OF CONSTRUCTION

9.1 Procedure for Construction of Stabilized Base Course

9.2 Programme of Works with superimposed S-Curve

9.3 Quality Control

CHAPTER 10

10. Access Roads

CHAPTER 11

11. Hydro-geological Study

CHAPTER 12

12. Experimental Trial Section


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CHAPTER 13

13. CONCLUSIONS AND RECOMMENDATIONS

13.1 Main Conclusions

13.2 Basic Recommendations


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LIST OF TABLES

Table 2.1 –Soil sampling from Designated Locations of Runway Alignment Table 5.1.1 Typical Grading Characteristics of Isiolo Airport Subgrade Soils Table 5.1.2 Summary of BCS-Subgrade Material Test results for Isiolo Airport Table 5.2.1 Test Regime 1: Sample Bp3 Table 5.2.2 Test Regime 1: OBRM Table 5.2.3 Test Regime 1: OPMC Table 5.3.1 Particle Distribution Characteristics of Sub-base soils at Borrow Pit [BP3], Ruiri Table 5.3.2 Particle Distribution Characteristics of 0.6mm Quarry Dust from Kithima Quarry Table 5.3.3 Particle Distribution Characteristics of OBRM sample [BP3:Quarry Dust] Table 5.3.4 Neat Material Table 5.3.5 OBRM Subbase Material +Tensar Tx 170 Geogrid Table 5.3.6 OPMC Subbase Material Table 5.3.7 Summary Of The Test Results-Comparative Analysis Table Series 5.4.1 and Figures for Dynamic Cone Penetration Results for Isiolo Airport Table 5.3.2 CBR Data and CBRM Values from Dynamic Cone Penetration Results for Isiolo Airport - Runway

Ch0+000 to Ch1+500 Table 5.3.8 Summary and comparison of granular subbase materisl found in the vicinity Table 5.5.1 Lab Sieve Analysis Results of Coarse Aggregate for Isiolo Airport – Runway Table 5.5.2 Lab Sieve Analysis Results of FineAggregate for Isiolo Airport - Runway Table 5.5.3 Fineness Modulus of Fine Aggregate for Isiolo Airport - Runway Table 5.5.4 Lab Sieve Analysis Results of CRS for Isiolo Airport - Runway Table 5.5.5 Summary of Stone Quarries Materials Tests Results for Isiolo Airport in Isiolo Table 5.6.1 Summary of Bearing Capacity and Shearing Strength Parameters for Isiolo Airport Table 5.8.1 Summary of Consolidation Stress Parameters Derived from In-situ Tests Table 5.8.2 Summary of Consolidation Stress Parameters Derived from Laboratory UCSTests of Cement

Stabilized OPMC-[Chemical stabilization] Table 5.8.3 Summary of Consolidation Stress Parameters Derived from Laboratory UCS test of Cement-

Geogrid Stabilized OPMC-[Chemical - Mechanical stabilization] Table 5.9.1 Summary of Shear Stress Parameters Derived from In-situ Tests Table 5.10.1 Summary of Modulus of Deformation Parameters from Lab Test Results Table 5.10.2 Summary of Modulus of Deformation Parameters from In-situ Test Results Table 5.11.1 Summary of Modulus of Deformation Parameters from in-situ Test Results Table 5.12.1 Effects of curing period on OPMC Level 3 Table 5.12.2 Effects of curing period on Resulting, ER Composite Pavement Table 7.2.1 Summary of Major Design Considerations Table 7.2.2 Technical Specifications for Boeing Aircraft detailing the B737-800 Table 7.2.3 General characteristics of the Model 737-800 Aircraft Table 7.2.4 Maximum Pavement Loads of the Model 737-800 Aircraft Table 7.3.1 Comparison of Design Criteria - Physical, Strength & Bearing Capacity of Stabilized Materials Table 7.3.2 Comparisons of Spec. Criteria -Stabilized Natural Gravel & Design Parameters - This Study Table 7.3.3 Comparisons of Ranges of Elasticity Modulus for Structural Design from Various Sources Table 7.7.1 Summary of Main Design Parameters Adopted Table 7.8.1 Conversion Co-efficient for the calculation of TA Table 7.8.2 Summary of the structural capacity and deformation resistance of the composite pavement Table 8.2.1 Summary of Main Parameters Adopted for Analysis for Varying Designs Table 8.2.2 Structural Depreciation Factor for EXISTING Design option.


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LIST OF FIGURES

Plate 1.1 Fokker F50 Aircraft and the Boeing 737-800 Plane Plate 1.2: Part of Erected perimeter fence around the airport Plate 1.3 Site photo depicting condition of runway pavement

Plate 1.4 - Photos Superimposed on Sattelite Imagery showing the Airport

Figure 1.1 Sattellite Image of Kenya (Location of Isiolo)

Fig. 1.2 Lay-out of Isiolo Town

Fig. 1.3 Sattellite Image of Isiolo Airport in Isiolo Region, Kenya

Figure 1.4 – Location of Isiolo Town in Kenya.

Fig. 1.5 Map of Isiolo District in relation to surrounding district

Fig. 1.6 Major Landform and Soil map of Isiolo region

Fig. 3.1: Dynamic Cone Penetration Equipment

Figure 4.1 Effect of gradation index on Mechanical Stability

Figure 4.2 Effect of gradation index on Bearing capacity

Figure 4.3 Correlation between mechanical stability, MS and bearing capacity, BC

Figure 4.4 (a) - (h) Method of Enhancing Mechanical Stabilization of Geomaterials (After Mukabi, 2001a)

Figure 4.5 Schematic representation of Grading curves generating Graphical Lines Depicted in Fig. 4.16

(After Mukabi, 2001a)

Fig. 4.6 Graphical Representation of New Batching Ratio Method (After Mukabi, 2001a)

Fig. 4.7a Effects of Mechanical Stabilization on Elastic Modulus

Fig. 4.7b Effects of Mechanical Stabilization on the Elastic Limit Strain

Fig. 5.6.1 CBR Mean values at Chainages on Isiolo Airport Runway

Fig. 5.6.1 CBR Mean soak values at Chainages on Isiolo Airport Runway

Fig. 5.12.1 Graphical representation of the effects of Curing Period on the OPMC material

Fig. 7.1 General Dimensions of the Model 737-800 Aircraft

Fig. 7.2 Ground Clearances – Passenger Configurations Model 737-800 Aircraft

Fig. 7.3 Landing Gear Footprint for Model 737-800 Aircraft

Fig. 7.4 Landing Gear Loading on Pavement - Model 737-800 Aircraft

Fig. 7.5 Pavement thicknes determination using conventional approach

Fig. 7.6 Pavement thickness determination using OPMC GI-MC Technique

Fig. 7.7 Plan of the Airport showing the two pavement types with other details

Fig. 7.8 Plan View and MC Sand Column Details for BCS Subgrade Improvement

Fig. 7.9 Typical Cross-section A:

Fig 7.10 Plan View and MC Sand Columns Details For Section A

Fig. 7.11 Typical Cross-section B

Fig. 7.12 Plan View and MC Sand Column Details for Cross Section B

Fig 7.13 Typical Cross-Section of the Apron Fig 7.14 Schematic Crossection of varying layers of proposed design, Cross-section A

Fig 7.15 Schematic Cross Section of varying Layers of Proposed Design, Cross-section B

Figure 8.1 Depiction of Determining Period and Level of Maintenance Based on the SCDR Model

Figure 8.2 Graphical Depiction of Depreciated Structural Capacity Factor and Resulting “WITH

Maintenance” Scenario as well as “WithOUT Maintenance”


Maintenance” Scenario as well as “WithOUT Maintenance” effect for USFAA-ICAO Design


Maintenance” Scenario as well as “WithOUT Maintenance” effect for Reviewed Design PROPOSED OPTION


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Maintenance” Scenario as well as “WithOUT Maintenance” effect for varying Designs

Fig 9.1 Programme of works with superimposed S-Curve

LIST OF FLOWCHARTS

Flow Chart 4.1 Proposed Batching Ratio Method (After Mukabi, 2001a)

Flow Chart 9.1 Overall method of construction

Flow Chart 9.2 Procedure for construction of Improved Subgrade

Flow Chart 9.3 Procedure for construction of OPMC stabilized Base/Sub-Base Course

Flow Chart 9.4 Procedure for construction of the Asphalt Concrete wearing Course


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LIST OF EQUATIONS

qq

imcu

vmcu

mc PIq

q

(4.1)

EUEU

imc

vmcmc PI

E

E

50

50

(4.2)

EmEm

imc

vmcmc PI

E

E

max

max

(4.3)

qq

OPMC

imcgi

gl

OPMC

umcgi

gl

mc PI

fCBR

fCBR

1

1

(%) (4.4)

(%)35m

BC

glgiCBR

PI

(4.5)

qq

imcgigl

umcgigl

mc PICBR

CBR

ln

ln

(%) (4.6)

scscscsc ln (%) (4.7)

glglDMC PIln (4.8)

w

Bp

pd PIeAPI (4.9)

mcdBm

mmcw DeAD

(4.10)

giwglwdr CBRln (4.11)

gidglddr CBRln (4.12)

girglwMr Mln (4.13)

NSPT = NNS {D2/Di}2 × D12/d × Wh/W140 × Hd/D30 (4.14)

N60 = (4.15)

(4.16)

4.17)

(4.18)

(4.19)

OPMCgiugl fqCBR }{ (%) (4.20)

OPMC

gi

gl

u fCBR

q 1

(kgf/cm2) (4.21)

qq

OPMC

imcgi

gl

OPMC

umcgi

gl

mc PI

fCBR

fCBR

1

1 (%) (4.22)

rr S

S

S

US CBRCBR1.09.0

500 (4.23)

BA CSR (4.24)


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SRSRSR /' (4.25)

CSRK CSRI

I

.

max

(4.26)

NCoc

o

NC

o

NCNC

ooc

CSRAKK

qKq

..

. maxmax

(4.27)

NC

C

NC

f

OC

C

NCOC

O

NC

O

NC

OOC

fp

PP

CSRAKK

Kq

'

''

'

. (4.28)

NC

fNCOC

O

NC

O

NC

OOC

fCSRAKK

K '1

'

. (4.29)

ij

KiC

ijo

jii

iC

iijT

P

PP

e

CHS

01,1

10log1

(4.30)

0010 /log PPP

eC i

ci

(4.31)

)110(0 i

k

scij PP

(4.32)

0455.0'0422.0SR (4.33)

f

fuNf

B

AqA max)('

(4.34)

max

max1

31'2'

qp

qSin

f (4.35)

3

1

'

15.0 max

'

Sinqp f

(4.36)

3

1

'/

15.0'

max

max

ffUNf

fBAqASin

qp

(4.37)

giglu CBRq ln (kgf/cm2) (4.38)

(4.39)

(4.40)


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(4.41)

(4.42)

(4.43)

(4.44)

(4.45)

= } (4.46)

eff

DISC

eff

DR x7.0 (4.47)

)/()0104.00996.0(

250

max cmkgfxq

EE n

q

u

ij (4.48)

)/(10139 20782.0

max cmkgfxexxE uqmC

dg

ij (4.49)

6.0'2 ))(1()17.2(2360 oo eeG (4.50)

(%)

max

50

Aij

a

ij

ELS

ij

aij

ELSa (4.51)

(4.52)

(4.53)

(4.54)

gbidSBNgbidSNpgbdSNq qqqqqqoCCCCCCn 2/1 (4.55)

q

C

CqN

ScSSS

1 (4.56)

q

C

CqN

dcddd

1 (4.57)

2sin1qr gg (4.58)

tan2egc (4.59)


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v

msecidfc tePPtfR ,,,,, (8.1)

o

ijyi

oc

f

oc

f

oc

fdh fqpf ,,',,',',' (8.2)

4tpE =

442 361 StVV PCC (8.3)

4

.stIII P (8.4)

K = vLEF (8.5)

o

ht

ord thec5.02

0

2sin (8.6)

0

5.022

0

2

0

5.022

0

222

0

22

0 sin5.0)( thwfthwCoshweCtE ra

ht (8.7)

22 2/12/1)(

rrda fdt

d

dt

tdE (8.8)

02

arctan22

0

h (8.9)

5.02222

0

0

4hw

fb (8.10)

5.0224

0

4h

fb (8.11)

2

0fb (8.12)

22

0

2arctan

hw (8.13)

iwt

rdrdrd eZtZ1 (8.14)

tZZG

t

n

n

n

n

n

rd

n 2

3

2

2

2

2

(8.15)

Zik

n

Zik

n

n

rdnn eFe (8.16)

Zik

m

Zik

nnnnnn eFeEGik (8.17)

n

n

nG

pk (8.18)

nn

nn

nmfe

feA (8.19)

twZKi

n

tKi

nn

rdn

rdn

n

eF

e

ttZ 2

2

2

1 (8.20)


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twZKi

n

tKi

n

n

n

rdn

n

n

eF

eik

2

(8.21)

gn

s

212 (8.21)

012

1****

1 Dijijijijy Rxxf (8.22)

vp

ij

vp

ijij dxdeABdx *

1

*

1

* (8.23)

21

vp

ij

vp

ij

vp deded (8.24)

0')1(

'1*~21

****1 mamnMijxijijxijg

(8.25a) 01~ '

)1(

'**

0 mamnmb Mf (8.25b)

''*~mcmnM (8.26)

BA CSR (8.27)

CSRK CSRI

I

.

max (8.29)

NCoc

o

NC

o

NCNC

ooc

CSRAKK

qKq

..

. maxmax (8.30)

NC

C

NC

f

OC

C

NCOC

O

NC

O

NC

OOC

fp

PP

CSRAKK

Kq

'

''

'

. (8.31)

NC

fNCOC

O

NC

O

NC

OOC

fCSRAKK

K '1

'

. (8.32)

( ''/'exp1 '

0

*' dZZZZT

ij

ZO

ij (8.33)

01~

'

'

*21

****

1b

bMxxg

mb

m

nijijijij (8.34)

01~

'

'**

0b

bMf

mb

mnmb

(8.35)

b

bM

mb

mn '

'*~

(8.36)

rfeffSCRL

e

SC xRDfff .

Re (8.37)

SB

C

SB

f

BC

C

BC

f

AC

C

AC

fRSF FxCFxCFC01.01 (8.38)

15.1log t

e

SC

t

SC Nxff (8.39)


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SCtSCtSCSCt CNBNAf (8.40)

(8.41)

(7.1)

(8.42)

(8.43)

(8.44)


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NOTATIONS, SYMBOLS AND TERMS

N = number of equivalent standard axle repetitions niv = initial number of vehicles daily in one direction Cv = proportion of commercial vehicles expressed in decimal form Gr = annual growth rate expressed in decimal form dl = proportion of vehicles using the design lane as a decimal (dl = 1 in this case) PDL = design life for the pavement in years SV = Slope Variance C = Lineal measurement of cracking per 100m2 area P = Bituminous patching in m2 per 1000m2 area RD = Rut depth in cm for both wheel tracks measured with a 3m straight edge

PSI = PSITR + PSISN + PSIMR

PSI = Total loss of serviceability (P0-Pt)

PSITR = Serviceability loss due to traffic loading (ESAL)

PSI SW = Serviceability loss due to swelling of roadbed soil

PSIMR = Serviceability loss due to deterioration of the quality of pavement material

t

A

t NP 10log

PtA = Actual performance related to PSI = Pt

A Pt

p = log Wt = predicted log Nt logwt = log (Rf x WT) = logWT + log Rf

Rf > 1 and log Rf > 0 log Rf = (log Wt – log WT) > 0

d = log Nt – log NT + d = Section survival of design period ESAL NT = Actual design period ESAL Nt = Actual ESAL to Pt

SCDLn = SCy

n - FRL (Sceff.)n

SCY = The total structural capacity required to support the overlay traffic over existing subgrade conditions

SCeff = The effective structural capacity of the existing pavement immediately prior to the time of overlay, and has reflected the damage to the point

FRL = The remaining life factor which accounts for damage of the existing pavement as well as the desired degree of damage to the overlay at the end of the overlay traffic where FRL < 1.0

n = A constant exponent which varies with the type of pavement system used in the analysis CBRus = 500(0.9-Sr) x CBRs

(0.1+Sr) CBRus = Unsoaked CBR CBRs = Soaked CBR Sr = Saturation level expressed as a fraction of 100 percent.

( s)f = SP

iSR

s max

( s)f = Time related swell factor ( s)max = Maximum Swell

SP = Surcharge related variable defined as a ratio of the applied surcharge pressure against the effective upper pavement layer surcharge pressure over the subgrade determined as the standard

surcharge pressure i.e. sp

ss

U

U

( SR)i = Initial Rate of Swell

PSIsw = 0.00335 VR PS (1-e DL) VR = Potential vertical rise due to swell in cm


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PS = Probability of swell as a percentage of total area subject to swell

SR = Rate of swell DL = Design Life Dmc = Design Moisture Content in % Vep = Annual evapotranspiration in metres/year LL = Liquid limit of subgrade material (%) CBRUS = Unsoaked CBR CBRS = Soaked CBR PI = Plasticity Index GLSC = Total Aggregate Loss converted in cm linear thickness for Loose Aggregate sections LT = Number of Loaded Trucks in thousands GLc = Total Aggregate Loss converted in cm lineal thickness for exposed sections

P = Performance Period = 4 years in this case (counted since the BD study) T = Annual Traffic Volume in both directions in thousands of vehicles R = Annual Rainfall in mm VC = Average percentage of gradient of the road F = Considered to be 0.037 as for lateritic gravels S2 = Variance xi = Value of ith sample N = No. of sample units CV = Coefficient of Variance S = Sample Standard Deviation xav = Average value is computed as VAV = Average Variable qu = Unconfined Compressive Strength

au

qu

r MPqM (5.1782.633 )

Mr CBR = 10.3 CBRd (MPa)

.Cor

rM = Corrected Resilient Modulus

MrCBR = 10.3CBRd (Design CBR)

Mr = (MrCBR-362)/Mr

CBR when MrCBR<362

Mr = 0.5(MrCBR-362)/Mr

CBR when MrCBR>362

AMr = Constant dependent on range of Resilient Modulus

Mr = -497 Wc + 5431 Mr = Resilient Modulus

WC = Variation in water content

ch

ch

d = Diameter of Chuckhole/Depth of Chuckhole

TR = TMf—T0

TR = Resulting Thickness TMf = Modified Thickn T0 = Original Thickness

AV

RT = Average Resulting Thickness ww Sr

R

SrCor

w xCBR1)9.0( 1500

Cor

wCBR = Corrected value to conform to CBR determined during wet season w

rS = Saturation level determined for Soils Sampled during the wet season

R = Ratio of CBR determined during the wet season to that determined during the dry season. In the case whereby either of the values is unavailable then the ratio of soaked to Unsoaked CBR can be adopted from the relation CBRs/CBRus = 0.97-0.027PI (Ref. eqn. (18))

Rf = Roughness Factor Ri = Initial Roughness Value Rt = Terminal Roughness Value


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n

i

iiGf xESALGI1100

1

R

eff

F

eff

T

eff RDRDRD

fsd = fRL = f (RDeff, PSF, RSF, PSI)

fsd = fRL = 1 - [RDeff. x (1- rf)]

rf = Combined contribution of other factors deemed to have had a reciprocal effect on the magnitude of the damaging effect. In this study,

Cf = CfP x fsd

Te = TeE

x CfP x fsd

TeE = Existing thickness.

CBRdDD = CBRd

BD x fsd

4.0

log97.319.9

CBR

DTNTA = Equivalent Thickness Index Total Asphalt Concrete

P(t) = instantaneous tyre force at time t, Pst = E[p(t)] = static (average) tyre force Cv = coefficient of varieties of dynamic tyre force E[ ] = expectation operator.

= 1+6 2

VC +3 4

VC (dynamic road factor)

I = parameter accounting for wheel configuration for both single or dual tyres

II = parameter accounting for tyre contact pressures. Intuitively

and ’ are dynamic versions related to the AASHO load equivalent factor (LEF) in the forms:

rd = rebound deflection

Co = constant representing the initial conditions of loading D =damping factor of the pavement structure related to layer stiffness t = response time measured

= angular frequency

= constant representing the initial position and condition of deflection measurement. fr is the force constant la =axle load.

Reconstruction of Runway Pavement for Isiolo Airport, Isiolo - Kenya |2011

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CHAPTER 1

1. INTRODUCTION

1.1 Background

The Kenya Airport Authority (KAA) commissioned Kensetsu Kaihatsu Consultants in the Rehabilitation and

Restoration of Isiolo Airport Pavement Project in Isiolo County to carry out a design of the airport pavement

facility using the Boeing 737-800 as the design aircraft with provision for future expansion.

Plate. 1.1 Fokker F50 Aircraft and the Boeing 737-800 Plane

1.1.1 Status of the site

The existing pavement is completely deteriorated with numerous portholes and the airport is completely in

disuse due to its current state. The runway width is less than 15m wide and 1.2km long. The arrival building,

control tower and fire and rescue buildings are non-existent and are not in the current contract works.

1.1.2 Works under Construction

The airport site is currently being fenced using precast concrete poles, barbed wire and mesh wire under a

separate contract.

Plate 1.2: Part of Erected perimeter fence around the airport


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1.2 Justification of the Project 1.2.1 Necessity for Rehabilitation of Isiolo Airport The district lacks basic infrastructure and is underdeveloped in comparison to other parts of Kenya (Republic of Kenya 1997). There are few bitumen covered road in the entire district most of which have been completed recently or are still under construction. The few rural roads are in poor condition and, therefore, impassable during the rainy season, hampering accessibility to livestock markets such as Nairobi and Mombasa. There is no piped water for households in the rural areas, while electricity, reliable telecommunication, schools, hospitals and other amenities are few and in poor condition. In general, the district is disadvantaged in natural and development aspects and falls within areas classified as “hardship area.” In Isiolo, human, floral and faunal survival is hampered by numerous natural and socioeconomic constraints. In particular, the 1997-1998 El Nino deluges in Kenya destroyed many infrastructures while the subsequent La Nina drought between 1999 and 2000 was even worse, as half the livestock in many vulnerable districts in the country perished (APD 2000). Isiolo District was hard hit by both of these phenomena as water conservation and conveyance structures were destroyed by the El Nino rains, while during the La Nina pastoralists from drier districts moved into Isiolo exacerbating an already overstretched ecosystem. There was an urgent need to supply relief aid to thousands of people and livestock. Many relief organizations pledged support but the situation was made particularly precarious by the poor infrastructure and lack of information with which to plan coordinated emergency recovery and mitigation interventions. It is with the above stated issues in mind that the Republic of Kenya envisioned to facilitate the development of Isiolo region to a modern city by the year 2030. In addition to the finished and ongoing infrastructural projects, the Isiolo airport facility will enable reliable and cost-effective movement of people, livestock products and ‘mirra’ from the region to markets in Nairobi and beyond. It will also give fast access of the region to humanitarian aids as well as security services in times of floods, droughts and conflicts since these are a characteristic of this region. Some of the major goals are:

To facilitate fast transportation of ‘Miraa’ from Isiolo and Meru region to Nairobi thus ensuring savings in cost and time as well as reducing road accidents in Nairobi-Meru highway caused by fast moving Miraa vehicles.

To promote eco-tourism in Isiolo and surrounding region. Isiolo has abundant wildlife and is home to Buffalo Springs, Shaba and Bisan-Adi Sanctuaries. The airport facility will attract increased number of tourists to the region and the Nearby Meru National Park due to the convenience of travelling by air as compared to travelling by road.

To open up the region to trade and investment opportunities in line with Kenya’s Economic Development plan Vision 2030 for Isiolo to become a tourist centre that will include casinos, hotels, upscale retail outlets and transport facilities given the vast land of the northern part of Kenya, available human resource (unemployed) and virtually unexploited natural resources.

1.2.2 Scope of Works The consultants, Kensetsu Kaihatsu Limited were commissioned by the Client, Kenya Airport Authority, to undertake a comprehensive geotechnical engineering analysis and assessment of the existing pavement by employing a Value Engineering (VE) approach and set up State-of-the-Art International Standards fostering engineering and scientific concepts that can be tailored and applicable in Isiolo, Kenya. The assignment included but was not limited to the following tasks:- i) Carry out pavement design using Boeing 737-800 as the design aircraft.

ii) Assess the state of the existing pavement.


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iii) Study the US Federal Aviation Administration (FAA) Advisory Circular “Airport Pavement Design and

Evaluation” AC 150/5320-6D, ICAO Aerodrome Design Manual, Materials and Specifications, ICAO

recommended practices as detailed in Annex 14 Volume 1, and any other relevant documents.

iv) Undertake comprehensive Site Surveys and Investigations.

v) Carry out detailed analyses and assessment of the test data obtained from both in-situ and laboratory

tests performed in Kenya.

vi) Assessment of the laboratory equipment and capability of the same to carry out material acceptance

and pavement control testing.

vii) Carry out material investigation, sampling and testing for the proposed runway.

viii) Perform tests on any other suitable material sites for aggregate sources, later to be utilized civil

works.

ix) Carry out geo-material improvement, mechanical, & chemical stabilization and testing for any non-

compliance materials and/or for purposes of enhancing the engineering properties of the compliant

materials.

x) Build capacity in terms of training manpower, and laboratory Technicians on test methods and quality

control.

Plate 1.3 Site photo depicting condition of runway pavement


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1.2.3 Isiolo Airport Project and Surrounding Areas

Fig. 1.1 shows the satellite image of Kenya and the location of Isiolo town relative to the country’s

boundaries. Figure 1.2 shows the layout of Isiolo town in relation to the location of Isiolo. Figure 1.3

depicts the satellite imagery of Isiolo Airport runway.

Figure 1.1 Satellite Image of Kenya (Location of Isiolo)

ISIOLO

KENYA

TANZANIA


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Fig. 1.2 Lay-out of Isiolo Town

Fig. 1.3 Satellite Image of Isiolo Airport in Isiolo Region, Kenya

1.2.4 Geophysical Details of Isiolo Airport in Isiolo county of Kenya

The site for the Isiolo Airport located in Isiolo, Kenya, and its geographical coordinates are 0°20'17" North and

37°35'28" East and its original name (with diacritics) is Isiolo.


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Airports in Isiolo and in the neighbourhood:

Garbatula Airport (distanced approximately 105.7 km)

Garissa Airport (distanced approximately 247 km)

Hola Airport (distanced approximately 341 km)

Marsabit Airport (distanced approximately 225 km)

Wajir Airport (distanced approximately 317 km)

Bura Airport (distanced approximately 308 km)

1.3 Brief Background of Project Area

The Study including Geotechnical Investigation was carried out for Isiolo Airport and the site photos are

depicted in Plate

Plate 1.4 - Photos Superimposed on Satellite Imagery showing the Airport


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Figure 1.4 – Location of Isiolo Town in Kenya.

Kenya is located in Eastern Africa between longitude 340 and 420 East, Latitude 50 North and 50 South. Kenya is the second largest of the East Africa countries (i.e. Kenya, Uganda, Rwanda, Burundi and Tanzania), has a spectacular landscape of mainly three physiographic regions namely the coastal plains to the east; the inland plateau; and the highlands. The Great Rift Valley that runs from north east of Africa through North western and south western Kenya down to Kenya is another landmark that adds to the scenic view of the country. The valley is dotted with unique lakes which include Lakes Turkana, Baringo, Bogoria, Naivasha, Nakuru, Elementaita, Logipi and Magadi.

Isiolo is a town in the Eastern Province, Kenya. It is situated in the Upper Eastern sub-region, and lies 285 kilometers north of Nairobi, the capital city of Kenya. The town grew around the local military camps, much of the population being descended from former Somali soldiers who had fought in World War I as well as other Cushitic-speaking pastoral communities and the Ameru community. The predominant population of Isiolo are the Oromo-speaking Boran and Sakuye as well as other Cushitic-speaking communities and the Bantu Ameru.In recent years there has been a steady migration from the neighbouring communities such Mandera, Wajir and Samburu, The most populous Division is Merit in the northern flank of the district. Isiolo town is the Headquarters of the district and the gateway to the northern half of the country. The town has an estimated population of 80,000 people, most of them living in the rural out backs of the District. There is an increasing urban population in the recent years, especially from as far as Moyale, Marsabit and Mandera. The Isiolo town is also becoming a centre of interest because of its newly acquired status as a resort city

Isiolo Town

http://en.wikipedia.org/wiki/Eastern_Province,_Kenya

http://en.wikipedia.org/wiki/Kenya

http://en.wikipedia.org/wiki/Nairobi

http://en.wikipedia.org/wiki/Military_camp

http://en.wikipedia.org/wiki/Somali_people

http://en.wikipedia.org/wiki/Soldier

http://en.wikipedia.org/wiki/World_War_I

http://en.wikipedia.org/wiki/Cushitic_languages

http://en.wikipedia.org/wiki/Ameru

http://en.wikipedia.org/wiki/Oromo_language

http://en.wikipedia.org/wiki/Bantu


http://en.wikipedia.org/wiki/Mandera

http://en.wikipedia.org/wiki/Wajir

http://en.wikipedia.org/wiki/Samburu


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cashing in on the popular Samburu and Shaba Game reserves and the Meru National Park, which have become preferred destinations after the famed Maasai Mara. Isiolo lies along the long A2 Road, leading towards Marsabit and Moyale much farther north. The town is served by Isiolo Airport, which is set to be upgraded to serve tourism and local exports. Isiolo is set to become a major part of Kenya's economic development plan Vision 2030. The plan calls for Isiolo to become a tourist center that will include casinos, hotels, upscale retail outlets, a modern airport and transport facilities. Isiolo District was designated as the Headquarters of the Northern frontier Districts by The British East Africa Protectorate in 1922, until the North Eastern was curved out as a separate province in 1963 following the Lancaster House Constitutional conference. The Meru National Park lies in the North East of the town. The town of Isiolo is small but cosmopolitan. With a scenic beauty including an eclectic mix of peoples and cultures, Isiolo is home to the Niger-Congo and Nilo-Saharan-speaking Ameru, Samburu and Turkana, as well as the Cushitic-speaking Rendille and Boran. The large Somali population is mainly the result of retired Somali soldiers who settled in the area after World War I. Isiolo is one of the 13 districts that form Eastern Province of Kenya. The district borders Marsabit district to the north, Garissa district to the south east and Wajir district to the east. It also borders Tana River, Meru North and Meru Central to the south and Laikipia and Samburu districts to the west. The district covers an area of 25,605 square kilometers and is divided into 6 administrative divisions namely Central, Garbatulla, Sericho, Merti, Oldonyiro and Kinna. There are 22 locations and 44 sub-locations. The district has 2 constituencies; Isiolo North and Isiolo South. There is only one local authority i.e. Isiolo County Council with 22 wards.

Fig. 1.5 Map of Isiolo District in relation to surrounding district

SAMBURU

MARSABIT

WAJIR

LAIKIPIA MERU

NYAMBENE

TANA

RIVRER

GARISA

ISIOLO

http://en.wikipedia.org/wiki/Meru_National_Park

http://en.wikipedia.org/wiki/A2_road_(Kenya)

http://en.wikipedia.org/wiki/Marsabit

http://en.wikipedia.org/wiki/Moyale

http://en.wikipedia.org/wiki/Economic_development

http://en.wikipedia.org/wiki/Vision_2030

http://en.wikipedia.org/wiki/Meru_National_Park

http://en.wikipedia.org/wiki/Niger-Congo_languages

http://en.wikipedia.org/wiki/Nilo-Saharan_languages


http://en.wikipedia.org/wiki/Samburu

http://en.wikipedia.org/wiki/Turkana

http://en.wikipedia.org/wiki/Cushitic_languages

http://en.wikipedia.org/wiki/Rendille

http://en.wikipedia.org/wiki/Boran

http://en.wikipedia.org/wiki/Somali_people


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1.3.1 Climate and Vegetation

Kenya’s climate varies from tropical type along the coast, temperate on the inland to arid in the North and North East part of the country. In the highlands, temperatures range between 10ºCand 20ºC.during cold and hot seasons respectively. The rest of the country has temperatures never falling lower than 200c. The hottest period spreads between January and February (25ºC - 31ºC) while the coldest period occurs between July and August (15ºC - 20ºC). The rainfall regime in Kenya is bimodal (March - June and October - December). The March - June rains are referred to as the long rains, whereas the October - December rains are generally known as short rains. The general range of temperature in Isiolo is between 12.7°C and 28.25°C. Isiolo district has three climatic zones: semi-arid, arid and very arid. The characteristics of these zones are as follows:

Semi-arid zone IV: This covers the Central and Kinna divisions (about 5 percent of the total area of the district). Rainfall here is 250-650mm per annum.

Arid Zone V: This covers Central Gerbatulla divisions and is 30% of the area. The rainfall here is between 300-350 mm per annum and can only support annual grasslands and a few shrubs.

Very Arid Zone VI: This area covers Merti and Sericho divisions which is nearly 65% of the district area. The rainfall here is between 150 and 250mm per annum.

1.3.2 General Topographic, Geographic and Existing Conditions

The topography of Isiolo is classified as 100% ASAL. The district is predominantly flat with low lying plains that rise gradually from an altitude of 200m above sea level at Lorian Swamp in the north to about 300m above sea level at Merti Plateau. Ewaso Nyiro River dissects the district into two. To the north is Merti plateau and to the south are the plains that rise to an altitude of 1000m above sea level with some inselbergs towards Nyambene Hills.

Fig. 1.6 Major Landform and Soil map of Isiolo region


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1.4 Relevant Documents and Records

Reference is made mainly to the following documents and records.

1. United States Federal Aviation Administration (US FAA) Advisory Circular No. 150/5320-6D

2. International Civil Aviation Organization (ICAO) Annex 14 Volume I – Aerodrome Design and

Operations

3. Aerodrome Design Manual, Part 3

4. The Kenya Roads Design Manual

5. Boeing 737-800 Guide to Aerodrome Design and Technical Data

6. The Civil Aviation (Aerodromes) Regulations, 2007

7. AASHTO Guide to Pavement Design

8. Transport Research Laboratory (TRL) Overseas Road Note 31, Berkshire, United Kingdom

9. Japan Road Association Pavement Design Manual

10. Materials Report and Test Results

11. Rehabilitation and Restoration of Pavements in Isiolo Airport Contract Documents


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CHAPTER 2

2. BASIC SAMPLING AND SURVEY PROCEDURES IN BRIEF

2.1 Preliminary Field Survey

Continuous sampling has been undertaken for more and the general site condition assessment was carried

out visually, through datum location, GPS recordings, trenching, shallow soil profile examination by pit

excavation and basic soil characteristic evaluation.

Some representative observations of the Sampling Survey are presented in Table 2.1.

Table 2.1 –Soil sampling from Designated Locations of Runway Alignment

Sampling Location Material Description

Depth /Source Sampled

Quantity (Kg)

Layer of Utilization

1 Km 0+000 LHS BCS 0.0m ~ 1.0m 50 GI/Subgrade

2 Km 0+600 RHS BCS 0.0m ~ 1.0m 50 GI/Subgrade

3 Km 0 + 1200 LHS BCS 0.0m ~ 1.0m 50 GI/Subgrade

4 Kithima Quarry Crushed stones Dust >1 m 50 Sub-base/Base Course

5 Kithima Quarry Crushed stones ¼” >1 m 50 Sub-base/Base Course

6 Kithima Quarry Crushed stones ½” >1 m 50 Sub-base/Base Course

7 Kithima Quarry Crushed stones ¾” >1 m 50 Sub-base/Base Course

8 Kithima Quarry Crushed stones 1” >1 m 50 Sub-base/Base Course

9 Borrow Pit 1 Gravel >1 m 50 Sub-base/Base Course





14 Borrow Pit 6 LMD Sandy >1 m 30 Sub-base/Base Course

15 LMD River LMD Sandy >1 m 50 Sub-base/Base Course

16 River Archers post Sandy >1 m 50 Sub-base/Base Course

From the preliminary field observations and material classification, it was concluded that the existing soils

cannot provide adequate bearing pressures, capacity, strengths and deformation resistance for subgrade

ground necessary to bear the road pavement structure and therefore an improved subgrade layer is required.

2.2 Basic Sampling Regime

The basic sampling of disturbed soil samples was undertaken as follows:

a) Disturbed soil samples were sampled at every 20 centimetres for confirmation of uniformity and at

every 600 metres for laboratory testing from the boreholes at each of the 2 locations.

b) The Geomaterial samples were immediately transferred to water proof polythene bags in order to

preserve the moisture content as much as possible.

c) The samples were then sealed properly, tied and appropriately labeled. Details of soil strata

encountered at each sampling location were recorded accordingly prior to sending them to the

respective Materials Testing Laboratories.


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Geological and Soil Survey

Geological and soil surveys mainly associated with the stability of the foundation ground in relation to the

original ground prior to cutting, studying the conditions of weathering, strike and inclination of stratum, and

the properties of joints and cracks of the existing rock were out of the scope of this Study.

As a consequence, the shape and size of Geomaterials, the conditions of matrix, the geological properties of

the soil masses, soil mechanical characteristics of the problematic soils, and the geological characteristics of

the ground were not critically examined.

Groundwater Survey in General

The stability of the ground decreases due to seepage of water whereby drastic reduction in bearing capacity

and deformation resistance tending to failure can occur easily.

In order to effectively carryout analysis on the characteristics of the generating mechanisms and the degree of

extent of damage it causes to the stability of the foundation ground, it is considered vital to determine the

groundwater conditions within and around the possible failure zone location constituting of location of

groundwater – flowing layer, fluctuation in water level, flow of groundwater, runoff path, current speed,

quality and temperature of groundwater as well as variation of these factors with seasonal changes. The

failure zone motion characteristics and the generating mechanisms can effectively be examined by correlating

the hydrological data and groundwater levels. Observations of the seasonal fluctuations in relation to the

vegetation in the Project area for purposes of studying the distribution of groundwater zone in comparison to

the results of the field survey are also vital.

For purposes of vertically surveying and analyzing the location of groundwater-flowing layer vis a vis the flow

conditions, water contents are to be determined for the varying layers of the borelogs.

2.5 Ground Movement Survey in General

Ground movement survey is to be predominantly carried out by assessing and evaluating the general

stratigraphic column for purposes of examining the scale, direction of movement, and the generating

mechanisms of the failure in detail since slight cracks due to inhomogenity had been observed in some cases.

There are signs of underground cavities; this is from the DCP results analyzed in Chapter 5.


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CHAPTER 3

3. TESTING, INVESTIGATION AND ANALYTICAL REGIMES

3.1 Design Criteria of Testing, Investigation and Analytical Regimes

3.1.1 Preamble

The Design Criterion is based on the RR concept which enhances the chemical – mechanical modes of

stabilization. Ground Improvement and Moisture Control techniques are also used in the improvement of

the existing BCS subgrade. The properties of the different Geomaterials from different borrow pits within

vicinity of the airport are enhanced by the use of the OBRM and OPMC techniques. Tensar Geogrids have

been incorporated in the RR technique to improve and enhance the durability of the composite pavement

particularly at later stages of loading. The above techniques are unique, researched oriented new generation

design and construction concepts and are geared towards Value Engineering.

3.1.2Postulated Failure Mechanism of Pavement and Subgrade Layers

Based on Case Study Analysis of in-situ ground behavior as well as field and laboratory data within the

East African Region, it is considered that, for the layers overlaying rock and located within shallow

depths, failure may predominantly be prompted by rapid moisture~suction variation and the combined

components of dynamic loading and pore pressure increase effects.

These effects may then culminate in the states briefly summarized here below for the respective layers.

(1) Expansive Overburden Soil Layers

This would result mainly in the reduction of density, bearing capacity, strength and deformation

resistance primarily as a result of decrease in angle of shearing resistance and shearing stress.

(2) Lower Sandy Clayey Layers

Crack propagation at the joint within the lower sandy clay layers may occur mainly due to the

reduction in confining stress as a result of increased pore water pressure combined with the

effects of dynamic loading due to traffic.

The shear failure planes and differential settlement measured and observed during most case

studies indicate that the failure tendency may propagate towards a critical state as excitement due

to dynamic loading increases.

(3) Main Objectives of Regimes Design and/or Choice Criteria Adopted

In general, the regimes were designed and developed in order to determine appropriate design

measures by establishing the following.

(a) Effectively assess and evaluate the field conditions including the propensity of ground failure

motion and behaviour, failure mechanisms and the direction and rate of failure where possible.

(b) Correlate as comprehensively as possible, the failure mechanisms due to changes in environmental

factors.

(c) Estimate groundwater-flowing layer and the flow conditions as precisely as possible.

(d) Examine the scale, direction of movement and generating mechanisms of the possible failure zone.

(e) Determine the necessary engineering parameters to determine a cost-effective and value

Engineering (VE) based foundation and structural design.

(f) Predict as precisely as possible, future failure or stability mechanisms.

(g) Predict future structural performance and design life of the ground performance and foundation


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structure.

(h) Propose effective methods of maintenance including emergency countermeasures for future protection

works.

However, it is important to note that items (c) ~ (h) are out of scope of this Report.

3.2 In-Situ and Laboratory Testing

3.2.1 Determination of Basic In-Situ Material Properties

Conventional testing techniques were applied to determine some basic physical properties of the in- situ

materials sample from the boreholes.

In-situ natural moisture content, Atterberg Limits, sieve analysis measurements and sieve analysis were

carried out for the varying layers for disturbed samples extruded from the respective boreholes.

3.2.2 Brief Introduction of In-situ and Laboratory Tests Undertaken

(1) Laboratory Tests

The laboratory tests performed included Atterberg Limits, Specific Gravity, Dry and Bulk Density

Sieve Analysis, measurement of Natural Water Content, Bearing Capacity test, Shear resistance and

consolidation tests.

(2) In-situ Tests

The in-situ tests undertaken included Soil Classification, Dynamic Cone Penetration Test (DCPT) and

Geophysical Survey by conducting Geo-electric Prospecting.

3.3 Summary of Laboratory Methods of Testing

The laboratory tests were performed on proposed materials under close supervision at the

laboratory.

All laboratory tests were performed in accordance with the Standards presented in Table 3.1. The

analyzed test results are presented under sub-section 5.1 of Chapter 5 of this Report.

3.3.1 Specific Gravity

Specific gravity tests were conducted in accordance with AASHTO T-100, on representative

samples of course aggregate. A sample of aggregate is immersed for 24 ± 4 h to essentially fill the pores.

It is then removed from water, the water dried from the surface of the particles, and the mass

determined. Subsequently, the volume of the sample is determined by the displacement of water

method. Finally, the sample is oven-dried and the mass determined.

3.3.2 Atterberg Limits

Atterberg limits were performed in accordance with AASHTO T-89/T-90, on soil samples. The liquid limit

was determined by Casagrande cup method and the plastic limits were determined via “Rolling- Thread”

method. For liquid limit determination, four water contents with blow counts between 15 and 35 were

adopted. As for plastic limit, two (2) measurements were made. The tests data are compiled in Appendix A.


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3.3.3 Sieve Analysis

Sieving was conducted in accordance with AASHTO T-27/T-28, to determine the percentage of coarse

and fine-grained material. A small but representative soil sample is allowed to be dried in the oven at

110oC for a period of 24 hours. The dry soil is weighed and washed through No. 200 sieve (75 m), and then

the soil retained is collected and oven-dried. After drying, the soil is sieved through No. 2” to No. 200 sieves.

The proportion of soil retained on each sieve is noted, and the grain size distribution curve is plotted

together with hydrometer test results.

3.3.4 Natural Water Content

Three small but representative soil samples are selected from various locations of the water proof

polythene bags, weighed to determine the moist weight and allowed to be dried in the oven at 110 C for a

period of 24 hours. Subsequently, the samples are weighed to determine the dry weight. The difference

between the moist and dry weights is then computed and presented in percentage form.

This test was basically conducted in accordance with JIS A1203.

3.4 Summary of In-situ Methods of Testing

The in-situ tests were performed in the field under close supervision.

All in-situ tests were performed in accordance with the Standards presented in Table 3.2. The analyzed

test results are presented under sub-sections 5.2 ~ 5.10 of Chapter 5 of this Report.

3.4.1 Dynamic Cone Penetration Test

In geotechnical and foundation engineering, in-situ penetration

tests have been widely used for site investigation in support of

analysis and design. The Standard Penetration Test (SPT) and the

Cone Penetration Test (CPT) are two typical in-situ penetration

tests. While SPT is performed by driving a sampler into the

soil with hammer blow, the CPT is a quasi-static

procedure. Fundamentally, the Dynamic Cone Penetration Test

(DCPT) exhibits features of both the CPT and SPT.

The DCPT is performed by dropping a hammer from a

certain fall height measuring penetration depth per blow for

a certain depth. As a consequence, it is quite similar to the

procedure of obtaining the blow count N using the soil

sampler in the SPT. In the DCPT, however, a cone is used to

obtain the penetration depth instead of using the split spoon

soil sampler. In this respect, there is some resemblance with

the CPT in the fact that both tests create a cavity during

penetration and generate a cavity expansion resistance.

The DCP basically consists of upper and lower shafts. The

upper shaft has an 8 kg (17.6 lb) drop hammer with a 575 mm

(22.6 in) drop height and is attached to the lower shaft

through the anvil. The lower shaft contains an anvil and a Fig 3.1: DCP testing equipment


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cone attached at the end of the shaft. The cone is replaceable and has a 60 degree cone angle. As a

reading device, an additional rod is used as an attachment to the lower shaft In order to run the

DCPT, two operators are required. One person drops the hammer and the other records

measurements. The first step of the test is to put the cone tip on the testing surface. The lower shaft

containing the cone moves independently from the reading rod sitting on the testing surface throughout

the test. The initial reading is not usually equal to 0 due to the disturbed loose state of the ground surface

and the self-weight of the testing equipment. The value of the initial reading is counted as initial

penetration corresponding to zero blows.

Plate 3.1 DCP Testing at the site

The penetration rate was determined as a function of the bearing ground resistance and the results were

correlated directly with SPT blow count, CBR and UCS.

3.5 Schedule and Summary of Tests Performed

3.5.1 Laboratory Tests

Samples obtained from the material sites were tested in the laboratory considering the following basic

objectives.

Compaction Tests

To be undertaken for the basic purposes of:-

Specifying a suitable Design Moisture Content for field compaction.

Specifying a minimum Dry Density to be obtained in the field.

Determining the Moisture Content to be employed in moulding compressive strength

and CBR specimens.

Compressive Strength (UCS) and CBR Tests

To be undertaken with the basic objective of:-

Determining the suitability of the soil for treatment and comparing different mixtures.

Specifying the appropriate cement content to be used in the construction.

Provide a standard by which the quality of the field processing can be assessed.


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Durability Tests

These tests will be carried out specifically for:

Determining the suitability and extent of stabilization particularly for the sub-base and

base course material.

Investigate the suitability of stabilized soil for use under particularly severe

environmental and dynamic loading conditions.

(1) Conditions of Moulding

a. Type of Materials

In-situ base course material

In-situ sub-base material

In-situ subgrade material

b. Type of Treatment

Optimum Batching Ratio Method, OBRM

Optimum Mechanical-Chemical Treatment, OPMC

Cement Content and Geogrid

All material to be tested: 0, 1, 2, 3, 4, and 6% by weight for both UCS Tests and CBR

Tests.

The geogrid is Tensar TX 170G

(2) Number of Samples

A minimum of 3 No. samples for each testing condition was adopted.

(3) Modes of Curing

The modes of curing indicated below should basically be adopted for experimental purposes of

determining the most appropriate mode that is suitable for the Geomaterials to be tested.

Seven days cure under

moist conditions

Seven days soak

Compressive strength

or CBR Tests

Six days cure under

moist condition

One day soak


or CBR Tests

3 days cure under

moist conditions

One day soak


or CBR Tests

4 days cure under

moist conditions

Zero days soak

(Unsoaked)


or CBR Tests

Zero days soak

(Unsoaked)


or CBR Tests

Seven days cure under

moist conditions


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Method of Testing

Strength Tests

Preparation of specimens and testing for strength shall basically be conducted in accordance

with BS 1924 (1990) or ASTM D558-82 (Reapproved 1990) with some modifications to be

determined in relation to the actual prevailing field conditions.

Basic Method of Sample Preparation

Mix cement and material thoroughly at designated percentage ratio

of dry weight of material i.e. d

Cds

f

C CC where f

CC =

final cement content, d

CC = designated cement content, S = wet

density and d = dry density

To simulate field conditions of mixing leave the mixed material for

at least 30 minutes but not longer than one hour prior to compaction.

Compact the material applying the standard method to a final OMCf which should be

greater than the pre-determined OMCP by 10% i.e. OMCf = 1.1xOMCP (approximately).

Cure the sample under moist and moulded conditions for the designated curing period.

Soak the samples for the designated period of soaking.

Carryout the CBR or UCS strength tests accordingly


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Durability Tests

In-order to better simulate the extreme environmental and loading conditions on the Airport

Pavement Structure, the durability tests will basically be modified as follows.

Mold the specimens in the concrete or CBR

moulds in accordance with the standard

specifications.

Cure the test specimens under moist conditions for a period

of 7 days, weigh and measure.

Place in a 1100C oven for 3 hrs or in a microwave oven for a

period calibrated to ensure similar amount of loss in moisture

content.

Remove the specimens weigh, measure and compute MC.

Firmly brush each face of the sample with a stiff wire brush giving

two strokes to each face.

Weigh the samples again and record the percent loss of the sample

resulting from the brushing.

Repeat Steps 3 ~ 6 until the specimens have undergone 12

cycles


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Schedule of Tests

Table 3.5.1. Standard Tests for Soils and Gravels

Description of Test Equivalent Standard/

Specification

commonly used in

East African Region

JIS Equivalent

Standard/

Specification

No. of Tests

Recommended

Remarks

Moisture Content A1203 102

Atterberg limits AASHTO T-89/T-90 A1205/6 34

Determination of linear

shrinkage AASHTO T-91 A1209 4

Determination of specific

gravity of particles AASHTO T-100 A1202 17

Particle size distribution to

0.075mm (dry sieving) AASHTO T-27 A1102 17

Determination of particle

size distribution to 0.075mm

(wet sieving)

AASHTO T-28 A1103 17

Hydrometer analysis for

fine-grained soils AASHTO T-84 A1202 2

Organic matter content ASTM-1411 -

Total Sulphate content ASTM-C289 -

pH value -

Density-moisture

relationship

(2.5kg rammer – AASHTO

T99)

AASHTO T-99 A1210 17

Density-moisture

relationship

(4.5kg rammer – AASHTO

T180)

AASHTO T-180 A1211 17

Density-moisture

relationship

(Vibrating Hammer)

BS598 Part 104

(1989) -

specialized

Innovative

tests only

CBR of specimen statically

compacted to 100% MDD &

OMC at 4 days soak

AASHTO T-193 A1121 27

CBR at 95% MDD (MOD.

AASHTO) of specimens

dynamically compacted at 3

levels of compaction & OMC

at 4 days soak

AASHTO T-194 A1122 27

Sand equivalent AASHTO T-176 -

Field density (sand

replacement method) AASHTO T-191 A1214 -

Triaxial Testing (CUTC) Innovated -


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Notes

i. Innovative and In-situ Tests to be determined during the Study and charged from

the Contingency Account.

ii. Tests to be carried out in Isiolo, or Nairobi unless otherwise all testing facilities are

available on site.

iii. Highly qualified Staff to be assigned for undertaking the tests

Table 3.5.2: Standard Tests for Aggregate, Sand & Filler

Description of Test Equivalent

Standard/

Specification

commonly used in

East African

Region

JIS

Equivalent

Standard/

Specification

No. of Tests

Recommende

d

Remarks

Determination of particle

size distribution to 0.075mm

(ISO sieves)

AASHTO T-27 A1204

30

Clay, silt and dust in fine or

coarse aggregate AASHTO T-112 A1126

30

Flakiness index BS812 Part 105

(1989)

30

Relative density and water

absorption ASTM D-2049

30

Bulk density, voids and

bulking

30

Aggregate crushing value

(ACV)

BS812 : Part 110

1990

30

Soluble chloride content BS812 Part 117

(1988)

-

Los Angeles Abrasion Value

(LAA) AASHTO T-96

30

Sodium or magnesium

Sulphate soundness AASHTO T-104

30

Average least dimension

(ALD) of aggregate

BS812 Part 1

(1975)

-

Crushing ratio (CR of

aggregate) BS812 Part 110

-


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Table 3.5.3: Standard Tests for Cemented Materials


Standard/

Specification

commonly used in

East African

Region

JIS

Equivalent

Standard/

Specification

No. of Tests

Recommende

d

Remarks

Density – moisture

relationship

(2.5 kg rammer – AASHTO

T99)

AASHTO T-99

34


relationship

(4.5 kg rammer – AASHTO

T180)

AASHTO T-190

34


relationship

(V.H)

AASHTO T-99/T-

180 BS1924 : 1990 A1216

34

Determination of the

Unconfined Compression

Strength (UCS)

AASHTO T-134/T-

208 BS 1377 (1990)

Part 8

A1216

34

Effect of immersion in water

on the UCS

AASHTO T-134/T-

208 BS 1377 (1990)

Part 8

A1121

17

CBR at 95% MDD (MOD.

AASHTO) of specimens

dynamically compacted at 3

levels of compaction & OMC

at 7DC + 7DS

AASHTO T-193

17

Cement content of cement

treated material NITRR (1984)

4

Lime content of lime treated

material BS 1924 : 1990

4

Initial consumption of lime

(ICL) BS 1924 : 1990

4

Durability Tests BS 1377 : 1990 Part

5

17


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2. Durability Tests

Table 3.5.4 Conditions of Testing for Durability Tests

Type of

Tests

Conditions of Testing

Material

Type

Variation in

Cement

Content

Modes of

Curing

No. of

Samples

Total No. of

Tests

Wetting/

Drying

Cycles

1 3 1 3 9

3.5.2 In-situ Tests

The in-situ tests undertaken in the field are summarized in the schedule presented in Table 3.5.5.

Table 3.5.5: Schedule of Standard In-situ Tests


Standard/

Specification

commonly used in

East Africa region

JIS Equivalent

Standard/

Specification

No. of Tests

recommended

Remarks

Drilling ASTM D1586 A1219 0

Soil classification BS 5930 A1205/6 >36

Disturbed sampling >36

Dynamic Cone Penetration TRRL (1990) >34

Geophysical survey 0

3.6 Proposal for Performance Specification for the Geogrid

Comprehensive research will be undertaken to determine the contribution of the geogrids to the overall

pavement structure.

The performance engineering properties of the geogrids shall be determined based on the scientific and

engineering concepts and other designed methods of testing. The enhancement of the different engineering

properties shall be construed to form the performance based specifications of the geogrids. The parameters to

be determined are tensile strength, compressive strength, structural capacity, modulus of elasticity etc


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CHAPTER 4

RELEVANT ENGINEERING CONCEPTS AND THEORIES APPLIED

This Chapter presents the relevant fundamental engineering concepts and theories that were applied in

carrying out the data analyses.

Several State of the Art analytical tools developed on the basis of innovation and long-term research form the

basis of methods applied for analyzing the results presented in Chapter 5.

4.1 Outline of Methodology of Data Analysis, Evaluation and Criteria for Suitability

Data analysis, evaluation and subsequent establishment of appropriate design criteria, method of construction

and desirable field quality control techniques is to be established on the basis of precise analytical tools based

on recently developed research oriented quasi-empirical relations on foundation engineering and construction.

This should be undertaken with the concise objective of enhancing the precision of the methodology adopted.

4.2 Determination of Basic Parameters

4.2.1 Standard Soil Model Expressions

In order to establish the magnitude of change of the physical properties of the existing foundation

Geomaterials and their corresponding effects on the bearing capacity, strength, moduli of deformation, basic

parameters such as natural moisture content (win), Atterberg Limits (PI, LL, WL, & LS), Specific Gravity (Gs),

voids ratio (e), dry density ( d) and degree of saturation (Sir) were determined based on the standard soil

model expressions.

In general terms, plasticity index is a function of the amount of clay present in a soil, while the Liquid Limit and

Plastic Limits individually are functions of both the amount and type of clay. High plasticity indices are

analogous to high water contents whose lubricating effect of the water films between adjacent soil particles

tends to reduce the mechanical stability, strength and deformation resistance. This phenomenon is

quantitatively illustrated by the following generalized empirical equations.

qq

imcu

vmcu

mc PIq

q

(4.1)

EUEU

imc

vmcmc PI

E

E

50

50

(4.2)

EmEm

imc

vmcmc PI

E

E

max

max

(4.3)

Where,

Mc = γmcMcu/Mci (Moisture Content Variation Factor),

UMC=Ultimate Moisture Content,

Imc=Initial Moisture Content,

and,


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γmc = 0.53 for expansive soils such as black cotton

= 0.35 for natural gravels and lateritic materials

= 0.28 for OPMC Stabilized materials

uq = Peak strength determined from Unconfined Compression (UCS) Tests,

50E = Pre-failure modulus determined from UCS or CUTC tests,

maxE = maximum Young’s Modulus,

PI = Plasticity Index,

q = -0.0123, EU = -0185, Em = -0.0362 and q

= 0.535, EU = 0.823, EU = 1.9 are material

constants related to strength, pre-failure and Young’s modulus respectively.

Substituting for uq in Equation 4.1 from the relation between UCS and CBR in Equations 4.20 and 4.21, we

obtain,

qq

OPMC

imcgi

gl

OPMC

umcgi

gl

mc PI

fCBR

fCBR

1

1

(%) (4.4)

The following empirical formula that correlates the bearing capacity expressed in terms of CBR and the

Plasticity Index is also employed.

35m

BC

glgiCBR

PI

(%) 4.5)

Where,

gi= 0.97,

gl= 0.027 and BC = 0.564 being the gradient linear, gradient intercept and Bearing

Capacity materials constant of most tropical Geomaterials tested and,

CBRm is the measured CBR value obtained at a density corresponding to 95% MDD in accordance to AASHTO T-

180 Method D for various soaking and curing periods.

Substituting for uq from Equation in Equation 4.1, we obtain Equation 4.6 as follows,

qq

imcgigl

umcgigl

mc PICBR

CBR

ln

ln(%) (4.6)

Where,

gl= 12.9, and

gi= 36.5 being the gradient logarithmic, and gradient intercept materials constants

for most Geomaterials tested.


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4.2.2 Concepts Applied for Analyzing Impact of Environmental Factors

Environmental factors are known to highly affect the concepts of design, actual construction and ultimate

performance of civil engineering structures. In this study, some comprehensive methods that may be effective

for evaluating the impact of these factors are proposed. A new concept of evaluating the deterioration of the

structural thickness as a result of infiltration of underlying material to the upper layers is also introduced.

Application of these concepts and methods show that the impact of environmental factors over a given period

of time can be more detrimental than commonly considered in most cases

The main objective of undertaking this research therefore was to develop new quantitative analytical

concepts and methods of effectively evaluating the impact of environmental factors such as geology,

topography and climate (seasonal changes) on the performance of civil engineering structures.

The major environmental factors considered which highly depend on topographic, geographical, geological,

climatic and other changes are depicted as follows:

Effect of Swelling

Recent research has shown that for most Geomaterials, swell can be contained by applying a surcharge

pressure of approximately 24KPa as can be derived from Equation (4.7).

scscscsc ln (%) (4.7)

Where,

sc Swell in relation to surcharge pressure

sc 12.9; logarithmic gradient constant for standard tropical Geomaterials

sc Surcharge Pressure in Kpa

sc 36.5; logarithmic intercept constant for standard tropical Geomaterials

Effect of Variation In Design Moisture Content

The selection of an appropriate design moisture content and density condition is critical to the design analysis

and subsequent construction Quality Control. The moisture content at which overlying layers strength should

be assessed is that which can be expected to be exceeded only rarely. Pronounced exceedance of this factor is

known to have adverse effects on the foundation structure.

glglDMC PIln (4.8)

Where,

DMC Design Moisture Content Ratio

gl

0.12; logarithmic DMC gradient constant for tropical Geomaterials

PI Plasticity Index of the Geomaterials to be utilized for construction

gi

0.7; logarithmic DMC intercept constant for tropical Geomaterials

Correction factors for the Plasticity Indices and the Design Moisture Contents respectively, during the wet and

dry seasons are defined in the following relations.


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w

Bp

pd PIeAPI (4.9)

Where,

pA = 12; linear gradient constant for PI for tropical Geomaterials

dPI Plasticity Index of the Geomaterials during the dry season

Bpe Annual Evapotranspiration Factor

BP = 0.02; Exponential constant for PI for tropical Geomaterials

wPI Plasticity Index of the Geomaterials during the wet season

mcdBm

mmcw DeAD

(4.10)

Where,

mA = 0.97; linear gradient constant for DMC for tropical Geomaterials

mcwD Design Moisture Content of the Geomaterials during the dry season

BMe Annual Evapotranspiration Factor

Bm = 0.03; Exponential constant for DMC tropical Geomaterials

mcdD Design Moisture Content of the Geomaterials during the wet season

Seasonal Effects On Bearing Capacity and Resilient Modulus

The combined effects of seasonal changes and soaking conditions on the bearing capacity and resilient

modulus of some Geomaterials is presented in Equations (4.11) ~ (4.13).

giwglwdr CBRln (4.11)

Where,

wdr = Wet to Dry Season Bearing Strength Ratio

gl

= 0.0022; logarithmic CBR gradient constant for tropical Geomaterials

gi

= 0.54; logarithmic CBR intercept constant for tropical Geomaterials

The relation between the CBR wet and dry season ratio vs. the CBR determined during the dry season is

correlated as follows.

gidglddr CBRln (4.12)

Where,

wdr = Wet to Dry Season Bearing Strength Ratio

gl

= 0.0022; logarithmic CBR gradient constant for tropical Geomaterials

gi

= 0.54; logarithmic CBR intercept constant for tropical Geomaterials


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girglwMr Mln (4.13)

Where,

wMr = Wet to Dry Season Resilient Modulus (Mr) Ratio

gl

= 0.0022; logarithmic Mr gradient constant for tropical Geomaterials

gi

= 0.54; logarithmic Mr Intercept constant for tropical Geomaterials

4.3 Bearing Capacity Analysis

4.3.1 Derivation of Correlations of N-value, UCS and CBR

Lacroix and Horn (1973) proposed that Non-Standard Penetration Resistance, NNS, could be correlated with

the Standard Penetration Resistance, NSPT, for drive samples or solid conical point apparatus such as the DCP,

static cone etc., which incorporated consideration of driving energy and distance of penetration. Their

reasoning was that the energy required to drive the sampler or cone through a given distance or depth (d) was

directly proportional to the square of the external diameter (De) and the distance of penetration, and inversely

proportional to the energy per blow {Weight of hammer (Wh ) multiplied by the height of drop (Hd)}, whence:

NSPT = NNS {D2/Di}2 × D12/d × Wh/W140 × Hd/D30 (4.14)

=

Where,

D2 = 50mm, D12 = 300mm, W140 = 65kg and D30 = 76mm

On the other hand, Skempton, 1986, proposed that SPT data can be corrected for a number of site specific

factors such as type of Geomaterials, overburden pressure, relative density, particle size, aging and over-

consolidation in order to account for efficiency and improve its repeatability, as well as precision. In this

publication, the procedures for determining a standardized blow count were presented, which allow for

hammers of varying efficiency to be accounted for. This corrected value is usually referred to as N60, since the

original SPT (Mohr) hammer has about 60% efficiency, and this is the word termed “standard” to which other

blow count values are compared. The SPT N-value corrected for field procedures and apparatus, N60, is

therefore given as:

N60 = (4.15)

Where,

, , ,


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On the other hand, comprehensive research undertaken over the past decade has developed empirical

equations based on field and laboratory data for tropical soils within the East and Central African Region that

correlate the SPT N-value and the Unconfined Compression Strength (qu) expressed as:

(4.16)

where,

Based on the foregoing and various other correlations, Mukabi et al. (2004, 2006 and 2007), established

empirical relations equating the SPT N-value ( , , and , to the inverse of the rate of penetration

determined from Dynamic Cone Penetration Tests (DCPT) as follows:

(4.17)

(4.18)

(4.19)

Where,

4.3.2 Derivation of CBR and qu Relations for Stiff Geomaterials

An empirical formula relating the bearing capacity based on CBR for materials where CBR ≥ 50, and

Unconfined Compression Strength (UCS) is defined as:

OPMCgiugl fqCBR }{ (%) (4.20)

Rewriting Equation (4.20) we obtain,

OPMC

gi

gl

u fCBR

q 1

(Kgf/cm2) (4.21)

where,

λgl = 14.4 and λgi = 46.6 being the gradient linear and gradient intercept of most Geomaterials tested in the

2001 Study and,


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opt

II

c

r

s

optOPMC BRBRRff is a strength and moduli ratio parameter derived from the influence of

OPMC Stabilization.

Substituting for uq in Equation (4.20) we obtain,

qq

OPMC

imcgi

gl

OPMC

umcgi

gl

mc PI

fCBR

fCBR

1

1

(%) (4.22)

In evaluating the resulting deterioration in foundation structural capacity as a consequence of moisture-

suction variations, relation (4.23) is adopted.

rr S

S

S

US CBRCBR1.09.0

500 (4.23)

where ,

CBRUS = Unsoaked CBR

CBRs = Soaked CBR

Sir = Saturation Level Expressed as fraction of 100 percent

4.4 Consolidation and Settlement Related Analysis

4.4.1 Estimation of Consolidation and Shear Stress Paths

As repeated loading progresses, the cumulative effects can be back analyzed by applying the concepts of

consolidation and shear stress ratio functions under normally consolidated (NC) conditions introduced by

Mukabi and Tatsuoka (1996) and Mukabi (2001d). In so doing, the initial stresses are computed from the

experimental results of full scale trial sections (Mukabi, 2002; Gono et al., 2003) .The cumulative stresses are

then derived by considering the average loading rate and cumulative repeated loading over a given period of

time. Once the maximum deviator and mean effective stresses are determined, the stress ratio functions,

defined from the following expressions proposed by Mukabi and Tatsuoka (1999b) and Mukabi (2001d) are

applied.

BA CSR (4.24)

Where,

A and B are material properties, and the consolidation stress ratio function CSR , which is

independent of the effects of loading rate, is derived from the relation max

1

~ qCSR, whereby '=

function of normalized angle of internal friction expressed as I

Q

A /' (A: An isotropic I:

Isotropic) and maxq = maximum deviator stress. 'can be determined from the quasi-empirical equation

(Mukabi, 2001d) expressed in general form as:


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SRSRSR /' (4.25)

where,

ASR and BSR are stress ratio constants and 'pqSR is the invariant stress ratio variable.

The antistrophic stress path is derived from the isotropic one by introducing a mathematical operator

proposed by Mukabi and Tatsuoka (1999b) expressed as:

CSRK CSRI

I

.

max

(4.26)

where,

max = (q/p’) at qmax, KI=1 and CSR= consolidations stress ratio. The modifier is applied in the relation

pq .

On the other hand, the invariant stresses and angle of internal friction under over consolidated (OC)

conditions were derived from the flowing correlations proposed by Mukabi (2001d).

NCoc

o

NC

o

NCNC

ooc

CSRAKK

qKq

..

. maxmax

(4.27)

where,

OC

OxK'sin fOCRK OC

Ox

and,

f

OC

OxK 'sin1

The corresponding mean effective stress, OC

fp 'and angle of internal friction

OC

f

' are given by:

NC

C

NC

f

OC

C

NCOC

O

NC

O

NC

OOC

fp

PP

CSRAKK

Kq

'

''

'

. (4.28)

and,

NC

fNCOC

O

NC

O

NC

OOC

fCSRAKK

K '1

'

. (4.29)

4.4.2 Analyzing Construction History for Settlement Prediction

Computation of total and initial settlement resulting from construction and surcharge of upper layers is

considered vital since this influence the characteristics of the foundation soils and the magnitude of their

engineering parameters.

In computing the total settlement, the generalized Equation (4.30) below was adopted.


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Computation of total and initial settlement resulting from construction and surcharge of upper layers is

considered vital since this influence the characteristics of the soils adjacent to the foundation structure and

the magnitude of their engineering parameters. In computing the total settlement, the generalized Equation

(4.30) below is adopted.

ij

KiC

ijo

jii

iC

iijT

P

PP

e

CHS

01,1

10log1

(4.30)

where,

Hi = Thickness of each layer in cm. Back Calculation of induced stresses and strains due to these effects

are derived from Equations (4.31) and (4.32) as follows.

0010 /log PPP

eC i

ci

(4.31)

)110(0 i

k

scij PP

(4.32)

Where,

ici

iCei

1

It is assumed that the stress is induced uniformly and that the magnitude of induced stress reduces

proportionally with depth. However, the quantitative reduction is average over the depth of each layer as a

logarithmic function of the summed reduction in voids ratio (e) and compression Index (CC).

4.5 Shearing Strength and Critical State Analysis

4.5.1 Analysis of a Soil Element along the Slip Failure Plane

Concepts developed based on recent research for the derivation of stress ratio functions related to

consolidation and undrained shear are adopted in comprehensively analyzing and evaluating the failure modes

and critical state conditions for design purposes.

The stress invariants and angle of shearing resistance are determined from the following relations.

0455.0'0422.0SR (4.33)

where,

fSR pqmax i.e. invariant stress ratio at failure and ' , which is fundamentally defined as '=

Sin-1 '''' rara under triaxial conditions is the Angle of Internal Friction of the

Geomaterials. The relation between ' and (qu)max adopted in this analysis is expressed in Equation

(4.34) as:

f

fuNf

B

AqA max)(' (4.34)

where,


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(qu)max values are expressed in KN/m2 and An = 0.08 A f = 106, B f = 3.83 are experimentally

determined constants.

On the other hand, considering that qmax = max)''( ra and rafP '2'31' then,

max

max1

31'2'

qp

qSin

f

(4.35)

From Equations (4.33), (4.34) and (4.35) the mean effective stress at failure '

fP is derived as :

3

1

'

15.0 max

'

Sinqp f (4.36)

or,

3

1

'/

15.0'

max

max

ffUNf

fBAqASin

qp (4.37)

A more universal empirical equation that considers all factors including the effects of OPMC stabilization,

variation in material properties, modes of mechanical and chemical stabilization, as a quantum of various

parameters is presented in Equation (4.32) below.

giglu CBRq ln (Kgf/cm2) (4.38)

4.5.2 Application of Modified Critical State Soil Mechanics

The development of the conventional Critical State Soil Mechanics(CSSM) concepts and theories was

predominantly based on the Rendulics principle of effective stress which states that for a soil in an initial state

of stress and stress history, there exists a unique relationship between its void ratio (e), and effective stress

( ). Within this context it is presumed that for a given, normally consolidated clay, failure occurs at a

unique line known as the Critical State Line (CSL) defined by , without allowing the stress paths to

locate above it at any one stage irrespective of drain conditions, strain rate and the stress path traversed

towards the CSL.

However, modern research has shown that this unique state does not exist for most of the natural clayey

Geomaterials for various reasons. Various Researchers for example, have reported that, the shapes and

magnitudes of yield envelopes are influenced mainly by the composition, anisotropy and stress history of the

clayey features.

Based on long term research, Mukabi and Tatsuoka (1992, 1995 and 1999) proposed some modification of

certain aspects of the existing theory of CSSM.

By determining the ratio of deviation of the Anisotropic stress path , as a function of the

Isotropic , they introduced a linear operator expressed as:


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(4.39)

Where,

Since , the equation defining the conventional can therefore be defined in the

modified form as:

(4.40)

On the other hand, the modified constant which would project the modified onto the space is

determined from the kappa function and the following relation.

(4.41)

where,

a = soil constant, /( a)I= soil constant determined during conventional Isotropic Consolidation,

=1.78, c/ / = CSR and =0.9

The modified Normal Consolidation and Critical State Lines in the space may therefore be defined as:

(4.42)

and,

(4.43)

The extrapolation of the consolidation constants to calculate the values of the stresses at failure under

undrained or partially drained conditions may therefore be given by Equations (4.43) and (4.44).

(4.44)

And,

(4.45)


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Another important aspect of this development is that as the bearing ground progresses towards Critical State

Conditions tending to failure, the shearing stress path deviates from constant conditions at a virtually

constant ratio.

Incorporating this concept, an empirically determined deviator stress factor, was proposed as indicated in

Equation (4.46).

= } (4.46)

where,

4.6 Deformation Resistance Analyses

4.6.1 Application of Deformation Concepts

The deterioration with time of the structural capacity of a civil engineering structure has been known to be

greatly influenced by the bearing capacity and resistance to deformation of the native soils.

For purposes of comprehensively studying this condition in the laboratory by varying a number of parameters,

dynamic loading was applied directly on the specimens in order to simulate critical conditions whereby the

upper layers of pavement structure would have deteriorated drastically leading to a gross loss of its structural

capacity. It was derived analytically that the effect of the damaging factor eff

D would reduce proportionally

by a factor 7.0

SC with the increase in structural capacity of the upper layers. This relation is expressed in

Equation (4.46).

eff

DISC

eff

DR x7.0 (4.47)

where,

eff

DR =Coefficient of Resulting Damaging Effect, 7.0

SC=Structural Capacity Factor, eff

DI =Coefficient of

Initial Damaging Effect.

4.6.2 Determination of Modulus of Deformation Parameters

Analysis of the elastic Young’s modulus and shear modulus to be adopted in characterizing the deformation

behavior of Geomaterials are derived from the following Equations.

For 2 < qn < 15kgf/cm2,

)/()0104.00996.0(

250

max cmkgfxq

EE n

q

u

ij (4.48)

where,

806.02 Ru qq

and


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2112.0/152663.124.2 cmkgfqSinceen u

qu

For 15< qn < 35,

)/(10139 20782.0

max cmkgfxexxE uqmC

dg

ij (4.49)

where,

45.189.142.0

u

C

dg q

and

755.05.0

Ru qqm

For qn > 35 then )/()0104.00996.0(

250

max cmkgfxq

EE n

q

u

ij

For OPMC stabilized aggregate, cementetious material and relatively hard rock, the following equation is

adopted.

For purposes of evaluating the influence and magnitude of change in voids ratio (e) on the maximum shear

modulus of Geomaterials, the following Equation is adopted.

(4.50)

Where,

6.0'2 ))(1()17.2(2360 oo eeG (4.51)

4.6.3 Computation of Linear Elastic Range

In analyzing the effects of dynamic loading, the linear elastic range is a vital parameter since it determines the

initial yield surface beyond which the behavior tends towards non-linearity and non-recoverability of elasticity.

In other words, the visco-elastic and plastic straining mechanisms leading to failure prevail. This concept is also

quite important in controlling the mode and magnitude of loading during stage construction.

Estimation of the linear elastic range or initial yield surface is made from the following Equation proposed by

Mukabi (1998).

(%)

max

50

Aij

a

ij

ELS

ij

aij

ELSa (4.52)

Where,


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ESL is a function of the level of max)( a and A is a constant depending on the physical properties of

the Geomaterials.

For most clays is defined as, 462max

50 xE

EELS

The analytical results based on this Equation can be adopted in predicting the magnitude of future settlement

as a result of dynamic loading as well as the corresponding possible deterioration in the structural capacity of

the foundation structure.

4.7 Geophysical Survey Analysis

The equipment adopted in this Study was a portable geo-electromagnetic sounding instrument based on the

time domain electromagnetic sounding technology. The modified system is based on the Transient

Electromagnetic Method (TEM) sounding technology which enable the conducting of subsurface sounding to

as deep as 300m depending mainly on the geological formation, ground conditions, environmental factors and

frequency mode.

Theoretically, an asymptotic estimation of signals for late stages of transience is considered. The development

of the electromagnetic signal with time, , for a late stage of the transience , for a

transmitting coil with a radius and a receiving coil with a radius , lying above the homogeneous half-space

with formation resistivity , magnetic permeability of vacuum and current , is described by the formula

proposed by Kamenetsky, 1997, expressed as follows:

(4.52)

The signal for does not depend on the radius of the receiving coil ( . Formula (4.45) is

also valid for a height above the surface of the half-space determined by the coil.

At a late stage of transience, the signal registered in the receiving antenna is caused by the currents induced in

the ring inside the section with the effective radius and the depth )]1/2, exceeding

the radius of the transmitting coil, .

The vertical magnetic field created by the coil is homogeneous within the limits of its area at , hence

registered signals which are proportional to the derivative of the magnetic field over time do not depend on

the station of reception.

At an early stage of transient ( and the identical coils ( , the signals do not depend on the

resistivity of the media or ground, hence:


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(4.53)

However, for a small receiving antenna the signal is proportional to the resistivity of the media or

ground, but does not depend on time. Consequently, this relation is expressed as:

(4.54)

4.8 Concepts Applied for OPMC Stabilization

4.8.1 Theoretical Considerations

In their natural state, most Geomaterials are usually deficient in one or more of the particle fractions required.

Consequently, mechanical stabilization plays an important role in achieving a pavement structure which,

under loading conditions, is appreciably resistant to shear and deformation. In developing the Optimum

Batching Ratio Method (OBRM), Mukabi (2001a) considered that; such Geomaterials would have a particle size

distribution that tends towards correctly proportioned ratio that would yield optimum density and adequate

strength to resist stress-induced deformation. This concept is demonstrated in Figures 4.8.1~4.8.3.

Figure 4.8.1 – Effect of gradation index on Mechanical Stability

Figure 4.8.2 – Effect of gradation index on Bearing capacity


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Figure 4.8.3 – Correlation between mechanical stability, MS and bearing capacity, BC

The theoretical point of departure in establishing this method is that soil is regarded as an assembly of

particles whose integrated motion can be characterized theoretically by basic concepts and fundamental

principles of continuum mechanics and models that consider probabilistic perspectives of microscopic state

and multi-dimensional analysis.

A summary of the theoretical and empirical basis for this method is presented in Figure 4.8.4 (a) ~ (h), in the

form in which the paper was presented at the 14th World Road Congress (IRF 2001) in Paris.

Figure 4.8.4 (a) - (h) Method of Enhancing Mechanical Stabilization of Geomaterials

4.8.2 Proposed Method of Determining Optimum Batching Ratio (OBR)

The mechanical stabilization method, developed on the basis of the foregoing theory, is represented

graphically in Figures 4.8.5 and 4.8.6 as well as Flow chart 4.1

Important factor Objective of

study

Develop a method of determining optimum Mixing ratios for Geomaterials with different grading characteristics in order to achieve; Enhanced strength (Bearing

Capacity)

Better Compaction characteristics

Greater resistance to wear

Enhanced resilience

properties

(c)

(e)

(d)

(f) (h) (g)

(a) (b)


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Figure 4.8.5 Schematic representation of Grading curves generating Graphical Lines Depicted

in Fig. 4.8.6

Fig. 4.8.6 Graphical Representation of New Batching Ratio Method


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Flow Chart 4.1 Proposed Batching Ratio Method

4.9 Concepts of Cementation on Soil Particle Agglomeration

Soil particle agglomeration is one of the most important characteristics required in geo-materials for their

application for the construction of geo-structures. Different Geomaterials with different intrinsic properties do

exhibit an enhancement into their properties with time. This is attributed to the enhancement of the physio –

chemical properties of the materials. When two or more Geomaterials with different physio-chemical

properties are batched together, their intrinsic properties are enhanced with time (Sirmoi, et al, 2011).

The following paragraph clearly explains the concept:

Figures 4(a) and (b) show the effect of Mechanical Stabilization on the deformation resistance parameters. As

can be noted in both cases, these parameters tend to increase as the Optimum Batching Ratio (OBR) tends

towards an optimum value.

The results in Figures 4(a) and (b) are consistent with the Cyclic Prestraining (CP ) models introduced by

Mukabi (2011d)[4], which are presented in Figures 5(a) and (b).

Figure 4 (a) Effect of Mechanical Stabilization on Elastic Modulus (Emax) and, (b) Effect of Mechanical

Stabilization on the Elastic Limit Strain, (εa)ELS

Determine Grading for both materials

Join the percentages passing for similar sieve sizes for both materials as shown in Fig. 4.3

Plot and join the lower and upper bound of the specification values as shown in Fig. 4.3

Assuming 50:50 Batching Ratio Line as the Phase transformation point, draw Translation Lines from the points where the sieve lines intersect the 50:50 BR Line to the specification Lines (Fig. 4.3)

Mark out the points of intersection at the intersection between the Sieve and Specification Lines (Fig. 4.3)

Calculate individual average Batching Ratios of material from points indicated on Fig. 4.3

Compute overall average Batching

Ratio

Calculate the percentages of the respective sieve size for the optimum grading curve

Plot values in grading envelop


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CHAPTER 5

5. MATERIALS CHARACTERIZATION AND ANALYSIS OF TEST RESULTS


Table 5.1.1 and the corresponding graph show the typical grading characteristics of the Isiolo Airport subgrade

soils sampled at varying depths and locations along some designated Airport Runway.

Table 5.1.1 Typical Grading Characteristics of Isiolo Airport Subgrade Soils

Sample time

(gm)

(gm)

(gm) (gm)

(gm) (%)

(gm) (%)

14 0.0

99.2

98.6

Initial dry sample mass

153

0.610

0.2

2 0.4

Fine percent 194

99.4

100.0

0.15 13 2.6 93.9

454

Specification According with BS 1377:1990-Wet and Dry Method

Min(%) Max (%)

Acceptance Criteria

Washed dry sample mass

91.7Washed dry sample mass + pan

0

3

1

4

41

97.8

96.6

0.6

0.3 3 0.6

0.425 3

0.8

99.0

Sample source

Sample N° :

100.0

97.2

26-Oct-10

495

Test date:

Pan mass

Fine mass

Sieve size (mm)

20

Acceptance Criteria

0.2

5 1

2

1

Sample Type BLACK COTTON SOIL

Retained mass (gm) % Retained (%)Cumulative passed

percentage (%)

Sample Date

Initial dry sample mass + pan 648

0.075 91.7

ISIOLO AIRPORT

41

0 0.0

0.6

2.211

Particle size distribution

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

Pass

ing

(%)

Sieves (mm)

On the other hand, Table 5.1.2 typical pre-treatment (pre-stabilization)/pre-consolidation basic physical,

mechanical and bearing capacity properties of the subgrade soils within the Airport Project Area.


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Table 5.1.2 Summary of BCS-Subgrade Material Test results for Isiolo Airport

1

2

3

4

5

6

7

89

# TESTED PARAMETERSTEST VALUE

REMARKS

Computed UCS (Mpa)

CBR@100%MDD - Soak

MDD - Kg per Cubic meter

OMC

Atterberg - LL

0.05

2.00

1,129.00

34.50

120.00

The subgrade soil has a lot of fines

CBR@100%MDD - Unsoaked 17.00

Atterberg - PI

Atterberg - LS

53.00

67.00

23.00

Atterberg - PL

5.2 The Development of the Test Regimes

To attain Optimum and a value engineered design, several Test Regimes were developed to help us achieve

the optimum designs. It involves the comparison of various designs options and modeling the different

structures in the Lab.

OBRM refers to the batched BP3 Gravel and 20% Quarry Dust materials while OPMC refers to OBRM with

cement and geogrids as chemical and mechanical stabilizing agents respectively. The materials in the three

different regimes are taken through different rates and modes of stabilization and curing and the change or

behaviour of the properties analyzed.

5.2.1 TEST REGIME 1: SAMPLE BP3

Neat 1 1 1 1 1 1 1

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

Granular Material-Gravel Stabilization Rate Mode of curing MDD OMC GRADING*PL LL PICBR

(%)

1d/c

UCS

KN/M2

3d/c

7d/c

7d c/s

1d c/s

1d/c

1d c/s

7d c/s

3d/c

7d/c

3%

7d c/s

1d/c

3d/c

7d/c

4%

BP3

1%

2%

1d c/s

3d c/s

7d c/s

3d c/s

3d c/s

1d/c

3d/c

7d/c

1d c/s

3d c/s


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5.2.2 TEST REGIME 1: OBRM

5.2.2 TEST REGIME 1: OPMC

Neat 1 1 1 1 1 1 1 1

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 1 2

1 1 1 1 1 1 2

3d c/s

3d c/s

PL LL PI GRADING*

1%

1d/c

3d/c

7d/c

Granular Material-Gravel Stabilization Rate Mode of curing MDD OMCUCS

KN/M2

2%

1d/c

3d/c

7d/c

1d c/s

7d c/s

1d c/s

7d c/s

3d c/s

1d c/s

7d c/s

CBR[%]

BP3+10% QUARRY DUST

4%

1d/c

3d/c

7d/c

1d c/s

3d c/s

7d c/s

3%

1d/c

3d/c

7d/c

Neat 1 1 1 1 1 1 1

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

1 1 1 1 1 1 2

4%

1d/c

3d/c

7d/c

1d c/s

3d c/s

7d c/s

3%

1d/c

3d/c

7d/c

1d c/s

3d c/s

7d c/s

OPMC [BP3+10% QUARRY

DUST + GEOGRID]

1%

1d/c

3d/c

7d/c

1d c/s

3d c/s

7d c/s

2%

1d/c

3d/c

7d/c

1d c/s

3d c/s

7d c/s

Granular Material-Gravel Stabilization Rate Mode of curing MDD OMCUCS

KN/M2PL LL PI GRADING*

CBR

(%)


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5.3 Correlation between Physical, Mechanical and strength Parameters

The typical pre-treatment (pre-stabilization)/pre-consolidation basic physical, mechanical and bearing capacity

for material tested from the existing borrow pit BP3 is summarized in Tables 5.3.1 to 5.3.7

Table 5.3.4 shows the UCS and Modulus characteristics of the neat material under soaked and Unsoaked

conditions.

Table 5.3.5 shows the UCS and Modulus characteristics of the OBRM material reinforced with TX 170 geogrid

under Unsoaked conditions.

Table 5.3.6 shows the chemical-mechanical stabilization results. The mechanical stabilization is provided by a

combination batched material and geogrids while the chemical stabilization is provided by 2% cement. The

high bearing capacity and strength values can clearly be noted.

Table 5.3.7 compares the results of the three test regimes.


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Table 5.3.1 Particle Distribution Characteristics of Sub-base soils at Borrow Pit [BP3], Ruiri

Sample time

(gm)

(gm)

(gm) (gm)

(gm) (%)

(gm) (%)

0.212 22.6 4.5 13.6

0

23.20.075 5.4

Pan mass

Project: Rehabilitation of Isiolo Airstrip

Retained mass (gm) % Retained (%)

BP 3 NEAT

Cumulative passed

percentage (%)

RUIRI

500

Sample Date

Sample source

Sample N° :

99.6

22.7

20

Acceptance Criteria

23.7

5

Initial dry sample mass + pan 906.7

Fine mass

Sieve size (mm)

19-Feb-11

500

Test date:

Washed dry sample mass + pan

2

15.2

118.6

49.2

27.2

28.8

18.1

0.6

0.3 23 4.6

0.425 30.8

9.8

54.4

0.0

6.2

4.6

0.15

5.4

17.4 3.5 10.1

GRADING CURVE

500

Fine percent 687.2

96.6

100.0

3.0

85.1

Min(%) Max (%)

Acceptance Criteria

78.1

14 0.4

78.1

38.7

University of Nairobi

Department of Civil & Construction Engineering(Highways Laboratory)

SIEVE ANALYSIS


176

10

7.0

78.4 15.7

35.2

2

1

6.3 57.2 11.4

390.4

Specification According with BS 1377:1990


0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

Passing (%)

Sieves (mm)


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Table 5.3.2 Particle Distribution Characteristics of 0.6mm Quarry Dust from Kithima Quarry

Sample Class Fine Aggregate

(gm)

(gm)

(gm) (gm)

(gm) (%)

(gm) (%)

0.212 13.4 2.7 13.6 3

14 0.0

88.0

35.2

0.6

0.3

0.425

5



SIEVE ANALYSIS


176

10

4.6

103 20.6

22.8

2

1

6.3 32.2 6.4

440.2




Sample source

Sample N° :

20

100

60 100

Fine percent 687.2

99.0

100.0

1.0

92.6

Min(%) Max (%)

Acceptance Criteria

88.0

9

Acceptance Criteria

100

32.2

0.15 0

8.7

9.5 1.9 11.7

GRADING CURVE

15

0

4.8

161

52.6

43.3

24.7

16.317.2 3.4

24.8 80

10.5

55.8

5 70

100.0

89 100

10015

19.8


Fine mass

Sieve size (mm)

22-Feb-11

500

Test date:

Pan mass



QUARRY DUST-0.6mm

Cumulative passed

percentage (%)

RUIRI

600

Sample Date

0.0

5.0

3.1

500

0

15.40.075 8.7

89

30

100

100

55

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

Passing (%)

Sieves (mm)


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Table 5.3.3 Particle Distribution Characteristics of OBRM sample [BP3:Quarry Dust]

Sample time

(gm)

(gm)

(gm) (gm)

(gm) (%)

(gm) (%)

0.075 39.1

19-Feb-11

500

Test date:

Pan mass



BP 3

Cumulative passed

percentage (%)

RUIRI

500

Sample Date

20

Acceptance Criteria

24.3

5


Fine mass

Sieve size (mm)

0.0

1.9

0

0.6

0.3 6.2 1.8

0.425 6.6

3.7

57.0

44.1

21

34

83.8

12.6

344.2

46.0

42.3

95.8

1.6

238.8

5.4

0.15

100.0

5.8 1.7 40.6

GRADING CURVE

Fine percent 687.2

89.0

100.0

6.8

Min(%) Max (%)

Acceptance Criteria

68.8

14 4.2

81.3

49.7



SIEVE ANALYSIS


176

10

7.7

25 7.3

38.4

2

1

344.2




Sample source

Sample N° :

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

Passing (%)

Sieves (mm)


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5.3.4. Neat Material

REMARKS

BP3-NEAT SUBBASE BASE1 1.23

2 52.00 Not<30% Not<80% Qualifies for subbase

59

3 1,486.00 NS NS4 19.10 " "5 45.00 " " Qualifies subbase

6 33.00 " "

7 11.00 Not<15% Not<15% Qualifies for subbase8 6.00 NS NS

SPECIFICATIONS REQMTS

CBR @ 100% MDD- 4 days soak

Atterberg - LS

# TESTED PARAMETERS TEST VALUE

Computed UCS (Mpa)

CBR @ 100% MDD- Unsoak

MDD - Kg per Cubic metreOMC Atterberg - LL

Atterberg - PL

Atterberg - PI

It is interesting to note that the CBR of the Neat Gravel-BP3 after 4days soak is 13% higher compared to the

CBR unsoak, uncured. This might be explained by the fact BP3 is lateritic gravel with very good cementetious

properties hence particle agglomeration is enhanced in presence of the moisture. More tests to ascertain this

phenomenon are underway.

5.3.5. OBRM SUBBASE MATERIAL+TENSAR TX 170 GEOGRID

The OBRM material is a batch of BP3 with 20% Quarry Dust (0.6mm).

5.3.6. OPMC SUBBASE MATERIAL

The OPMC material is a batch of BP3, 20% Dust and 2% cement.

SUBBASE BASE

1 - 1.80

2 Not<30% Not<80%

4 NS NS

5 " "

6 " "

7 " "

8 Not<15% Not<15%

9 - -

Atterberg - PI 10.00 Qualifies for base and subbase

Atterberg - LS -

Atterberg - LL 38.00

Atterberg - PL 28.00

MDD - Kg per Cubic meter 1,595.00 OMC 12.60

CBR@100%MDD - Unsoaked 120.00 Qualifies for base and subbase

OBRM

Computed UCS (Mpa) 2.88 Qualifies for base and subbase

TESTED PARAMETERS REMARKSTEST VALUE SPECIFICATIONS REQMTS

#

SUBBASE BASE

1 - 1.80

2 Not<30% Not<80%

4 NS NS

5 " "

6 " "

7 " "

8 Not<15% Not<15%

9 - -

Atterberg - PI 11.00 Qualifies for base and subbase

Atterberg - LS -

Atterberg - LL 38.00

Atterberg - PL 27.00

MDD - Kg per Cubic meter 1,615.00 OMC 12.80

Computed UCS (Mpa) 3.32 Qualifies for base and subbase

CBR@100%MDD - Unsoaked 138.00 Qualifies for base and subbase

# TESTED PARAMETERSTEST VALUE SPECIFICATIONS REQMTS

REMARKS


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5.3.7. SUMMARY OF THE TEST RESULTS-COMPARATIVE ANALYSIS

5.3.8. SUMMARY AND COMPARISON OF GRANULAR SUB-BASE MATERIAL FOUND IN THE VICINITY

From the tables above the following can be inferred:

The gravel at BP3 is of good sub-base quality. It has natural intrinsic cementetious behaviour. This

makes it posses’ high engineering properties in comparison to other materials within the location [see

table above].

The grading of BP3 is satisfactory but we will be required to add 20% Quarry Dust to improve on the

densities.

The strength properties, densities and particle of the neat BP3 material is enhanced by the inclusion

of the 20% quarry dust and 2% cement.

The cement used is Bamburi PowerPlus. It is reported that PowerPlus type of cement gains strength

immediate/sporadically after stabilization and after about 28 days the strength normalizes; PowerMax

gains strength with time and it’s expected to yield maximum strength after 28 days. Laboratory tests

and monitoring are ongoing to confirm this.

The OPMC batched material evidently shows improved properties. We have an increase of more than

150% in strengths after 3 day cure. Further tests are still on-going to ascertain the behaviour with

time and at different conditions as described in 5.2

From the 1 day cure results we can tentatively decide that our design will be BP3+20% Quarry Dust +

Tensar TX170 Geogrids + 2% cement is the optimum design.

BP3 OBRM OPMC SUBBASE BASE

1 1.23 2.28 3.32 - 1.80

2 52.00 120.00 138.00 Not<30% Not<80%

4 1,486.00 1,595.00 1,615.00 NS NS

5 19.10 12.60 12.80 " "

6 45.00 38.00 38.00 " "

7 33.00 28.00 27.00 " "

8 11.00 10.00 11.00 Not<15% Not<15%

9 6.00 - - - -

Atterberg - PI Qualifies for base and subbase

Atterberg - LS

# TESTED PARAMETERSSPECIFICATIONS

REMARKS

Atterberg - PL

TEST VALUE

OMC

Atterberg - LL

CBR@100%MDD - Unsoaked Qualifies for base and subbase

MDD - Kg per Cubic meter

Computed UCS (Mpa) Qualifies for base and subbase

TESTED PARAMETERS Computed UCS, qu Computed UCS, qu

MDD OMC LL PL PI LS (kgf/cm2) (Mpa)

kg/m3 % % % % % Top Bot Ave Top Bot Ave Top Bot Ave

1 BCS subgrade 1129 34.5 114.7 52.7 62.0 23.0 14.0 20.0 17.0 2 2 2 0.48 0.048929664

2 BP1 LMD gravel 1799.8 13.2 31.0 15.0 16.0 5.0 46.0 36.0 41.0 9.84 1.003058104

3 BP2 78 Tank Batt 1924.5 11.6 43.5 23.7 19.8 9.0 48.0 45.0 47.0 11.28 1.149847095

4 BP3 Ruiri 1486 19.1 45 33 11 6 52 51 52 12.36 1.259938838

8 BP5 Murero 1789.1 18.4 44.5 23.7 20.8 9.0 34.0 23.0 28.5 6.84 0.697247706

9 BP6 LMD Sandy 1835 14.8 36.0 12.0 24.0 6.0 8.0 8.0 8.0 1.92 0.195718654

0 0

0 0

0 0

3hrs Soak

CBR AT 100% MDD

Soaked

Sample Location

#

Unsoaked


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5.4 Dynamic Cone Penetration Test Results

The ground and Geomaterials characteristics under dynamic loading as simulated by the Dynamic Cone

Penetration determined in this Study, are summarized in the Tables below, while their behavior is graphically

characterized in the corresponding Figures.

Low bearing capacities and strength magnitudes were exhibited due to the fact that the existing subgrade is

Black Cotton soil with exceptions of locations which fell on the old runway.

Series 5.4.1 Tables and Figures for Dynamic Cone Penetration Results for Isiolo Airport


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0+120 WEATHER STATUS

LHS Temp:

Humidity:

Rainfall:

Precipitation Period

60o

Wind Status

CBR S/ No. No. of blowsCummulative

Blows

Initial

Reading (Hi)

Final

Reading (Hf)Level (Hf-Hi)

Penetration

Depth (mm)

Cumulative

Penetration

Depth (mm)

Penetration

Rate

(mm/blow) P

CBR (%)UCS, qu

(kgf/cm2)

N-Value

0 0 0 0 0 0 0 0.00

17.88 1 10 10 990 820 170 170 170.0 17.00 17.88 4.32 8.82

32.00 2 10 20 820 725 95 95 265.0 9.50 32.00 7.73 15.79

33.78 3 10 30 725 635 90 90 355.0 9.00 33.78 8.16 16.67

48.64 4 20 50 635 510 125 125 480.0 6.25 48.64 11.74 24.00

67.56 5 20 70 510 420 90 90 570.0 4.50 67.56 16.31 33.33

84.44 6 20 90 420 348 72 72 642.0 3.60 84.44 20.39 41.67

15/01/2011

DESIGN OF PAVEMENTS AND BUILDINGS AT ISIOLO AIRPORT - KENYA

DCP TEST RESULTS - PAVEMENTS

PENETRATION DATA REPORT

Chainage(km):

Location:

Lane no.

Offset(m):

Surface Type:

Cone angle

Zero error:

Test date:


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0+140 WEATHER STATUS

RHS Temp:

Humidity:

Rainfall:

Precipitation Period

60o

Wind Status

CBR S/ No. No. of blowsCummulative

Blows

Initial

Reading (Hi)

Final

Reading (Hf)Level (Hf-Hi)

Penetration

Depth (mm)

Cumulative

Penetration

Depth (mm)

Penetration

Rate

(mm/blow) P

CBR (%)UCS, qu

(kgf/cm2)

N-Value

0 0 0 0 0 0 0 0.00

17.37 1 10 10 980 805 175 175 175.0 17.50 17.37 4.19 8.57

30.71 2 10 20 805 706 99 99 274.0 9.90 30.71 7.41 15.15

37.53 3 10 30 706 625 81 81 355.0 8.10 37.53 9.06 18.52

46.06 4 10 40 625 559 66 66 421.0 6.60 46.06 11.12 22.73

56.30 5 10 50 559 505 54 54 475.0 5.40 56.30 13.59 27.78

67.56 6 10 60 505 460 45 45 520.0 4.50 67.56 16.31 33.33

76.00 7 10 70 460 420 40 40 560.0 4.00 76.00 18.35 37.50

82.16 8 10 80 420 383 37 37 597.0 3.70 82.16 19.84 40.54

15/01/2011

DESIGN OF PAVEMENTS AND BUILDINGS AT ISIOLO AIRPORT - KENYA

DCP TEST RESULTS - PAVEMENTS

PENETRATION DATA REPORT

Chainage(km):

Location:

Lane no.

Offset(m):

Surface Type:

Cone angle

Zero error:

Test date:


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The following derivations can further be made from these tables and figures.

a. Most of the locations on the carriageway of the existing pavement structure exhibit high bearing

strengths under conditions tested with averages of CBR 62%.

b. The average CBR mean results is about 62% for dry in situ conditions while the soaked conditions

gives average CBR mean of less than 5%. From the two CBR figures, it is prudent that the

subgrade/foundation Design considers options for moisture control in its design. We are

proposing the GI-MC method for the design and construction of the improved subgrade. This

because when the foundation is dry i.e. when moisture is controlled, the in-situ strengths are very

high compared when it is partially or completely soaked.

c. The Subgrade BCS soil has PI values of 67%. This indicates a very high value of fines and clay

minerals in its composition. The design needs to cater on how to prevent the contamination of

the Base/sub-base layers through infiltration/ingress of fines into the upper pavement layers

[base/sub-base]. The presence of fines into these layers will be very detrimental to the structural

performance of the pavement layers. The presence of fines will raise the Capillary action of the

layers and this will result in ‘soaking up’ of the layers and the subsequent reduction of strength.

d. From KM 0+000 to KM 0+700, the CBRM are greater than those from KM 0+700 to Km 1+400. This

is because of consolidation with time and the presence of the old dilapidated pavement from KM

0+000 to Km 0+700

e. The Design CBR of our design criteria is 62% since it is the CBR mean result when the

foundation/subgrade is Unsoaked. Conventionally, that is without the Moisture Control

techniques, the CBR mean is less than 5%.

The mean CBR values are shown in the following Tables 5.3.2.

Table 5.3.2 CBR Data and CBRM Values from Dynamic Cone Penetration Results for Isiolo Airport - Runway

Ch0+000 to Ch1+500 KM 1+400 RHS Soaked NMC= KM 1+400 RHS Partially Soaked KM 1+400 RHS Unsoaked NMC=% KM 0+000 CL 0 NMC=%

Penetration

Depth (mm)

Thickness, t

(mm)CBR (%) CBRP t x CBRP Penetration

Depth (mm)

Thickness, t


Depth (mm)

Thickness, t


Depth (mm)

Thickness, t

(mm)CBR (%) CBRP t x CBRP

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

480 480 0.63 0.86 412.21 100 100 3.04 1.45 144.86 289 289 5.26 1.74 502.59 105 105 28.95 3.07 322.42

672 192 1.58 1.17 223.78 140 40 7.60 1.97 78.64 359 70 21.71 2.79 195.29 145 40 76.00 4.24 169.43

838 166 1.83 1.22 203.09 160 20 15.20 2.48 49.54 519 160 9.50 2.12 338.87 170 25 121.60 4.95 123.86

0 -838 0.00 0.00 0.00 210 50 6.08 1.83 91.26 639 120 12.67 2.33 279.73 215 45 67.56 4.07 183.27

0 0 0.00 0.00 0.00 270 60 5.07 1.72 103.05 709 70 21.71 2.79 195.29 270 55 55.27 3.81 209.51

0 0 0.00 0.00 0.00 350 80 3.80 1.56 124.84 789 80 19.00 2.67 213.47 390 120 50.67 3.70 444.04

0 0 0.00 0.00 0.00 370 20 15.20 2.48 49.54 0 -789 0.00 0.00 0.00 495 105 57.90 3.87 406.22

0 0 0.00 0.00 0.00 410 40 7.60 1.97 78.64 0 0 0.00 0.00 0.00 595 100 60.80 3.93 393.22

0 0 0.00 0.00 0.00 430 20 15.20 2.48 49.54 0 0 0.00 0.00 0.00 670 75 81.07 4.33 324.60

0 0 0.00 0.00 0.00 450 20 15.20 2.48 49.54 0 0 0.00 0.00 0.00 0 -670 0.00 0.00 0.00

0 0 0.00 0.00 0.00 470 20 15.20 2.48 49.54 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 510 40 7.60 1.97 78.64 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 520 10 30.40 3.12 31.21 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 530 10 30.40 3.12 31.21 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 540 10 30.40 3.12 31.21 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 -540 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

Sum 839.09 Sum 1041.29 Sum 1725.23 Sum 2576.56

CBRM 1.00 CBRM 7.17 CBRM 10.45 CBRM 56.87


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KM 0+050 LHS NMC=% KM 0+100 CL KM 0+170 RHS KM 0+200 LHS

Penetration

Depth (mm)

Thickness, t


Depth (mm)

Thickness, t


Depth (mm)

Thickness, t


Depth (mm)

Thickness, t


0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.00 0

105 105 57.90 3.87 406.22 48 48 63.33 3.99 191.33 122 122 24.92 2.92 356.34 75 75 40.53 3.44 257.63

360 255 23.84 2.88 733.94 95 47 129.36 5.06 237.70 200 78 77.95 4.27 333.19 110 35 86.86 4.43 155.00

587 227 26.78 2.99 679.18 213 118 51.53 3.72 439.09 235 35 173.71 5.58 195.29 205 95 32.00 3.17 301.61

635 48 63.33 3.99 191.33 316 103 59.03 3.89 401.04 283 48 126.67 5.02 241.06 265 60 50.67 3.70 222.02

0 -635 0.00 0.00 0.00 415 99 61.41 3.95 390.59 355 72 84.44 4.39 315.88 325 60 50.67 3.70 222.02

0 0 0.00 0.00 0.00 525 110 55.27 3.81 419.02 437 82 74.15 4.20 344.49 370 45 67.56 4.07 183.27

0 0 0.00 0.00 0.00 570 45 135.11 5.13 230.91 510 73 83.29 4.37 318.80 450 80 76.00 4.24 338.87

0 0 0.00 0.00 0.00 630 60 101.33 4.66 279.73 575 65 93.54 4.54 295.06 510 60 101.33 4.66 279.73

0 0 0.00 0.00 0.00 0 -630 0.00 0.00 0.00 0 -575 0.00 0.00 0.00 585 75 81.07 4.33 324.60

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 -585 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

Sum 2010.67 Sum 2589.42 Sum 2400.12 Sum 2284.74


KM 0+300 CL KM 0+400 RHS KM 0+500 LHS KM 0+600 CL

Penetration

Depth (mm)

Thickness, t


Depth (mm)

Thickness, t


Depth (mm)

Thickness, t


Depth (mm)

Thickness, t


0 0 0.00 0 0 0 0 0 0 0 0.00 0 0 0 0.00 0

60 60 50.67 3.70 222.02 130 130 23.38 2.86 371.75 150 150 20.27 2.73 408.96 100 100 30.40 3.12 312.10

95 35 86.86 4.43 155.00 250 120 50.67 3.70 444.04 275 125 24.32 2.90 362.16 140 40 76.00 4.24 169.43

140 45 67.56 4.07 183.27 415 165 36.85 3.33 549.07 415 140 43.43 3.51 492.10 200 60 101.33 4.66 279.73

215 75 81.07 4.33 324.60 488 73 41.64 3.47 253.03 485 70 86.86 4.43 310.00 255 55 110.55 4.80 263.96

310 95 64.00 4.00 380.00 545 57 53.33 3.76 214.56 545 60 101.33 4.66 279.73 320 65 93.54 4.54 295.06

460 150 40.53 3.44 515.26 585 40 76.00 4.24 169.43 590 45 135.11 5.13 230.91 375 55 110.55 4.80 263.96

505 45 135.11 5.13 230.91 0 -585 0.00 0.00 0.00 0 -590 0.00 0.00 0.00 480 105 57.90 3.87 406.22

590 85 71.53 4.15 352.84 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 590 110 28.28 3.05 335.13

0 -590 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 620 30 43.43 3.51 105.45

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 -620 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

Sum 2363.91 Sum 2001.88 Sum 2083.86 Sum 2431.04

CBRM 64.32 CBRM 40.07 CBRM 44.06 CBRM 60.28 0+700 RHS NMC= KM 0+800 LHS Day NMC= KM 0+900 CL NMC= KM 1+000 RHS Day NMC=

Penetration

Depth (mm)

Thickness, t


Depth (mm)

Thickness, t


Depth (mm)

Thickness, t


Depth (mm)

Thickness, t


0 0 0.00 0 0 0 0.00 0 0 0 0.00 0 0 0 0.00 0

95 95 32.00 3.17 301.61 285 285 10.67 2.20 627.37 70 70 43.43 3.51 246.05 140 140 21.71 2.79 390.58

180 85 35.76 3.29 280.05 375 90 33.78 3.23 290.93 110 40 76.00 4.24 169.43 215 75 40.53 3.44 257.63

275 95 64.00 4.00 380.00 415 40 76.00 4.24 169.43 155 45 67.56 4.07 183.27 230 15 405.33 7.40 111.01

345 70 86.86 4.43 310.00 440 25 121.60 4.95 123.86 215 60 101.33 4.66 279.73 240 10 608.00 8.47 84.72

375 30 202.67 5.87 176.22 560 120 50.67 3.70 444.04 255 40 152.00 5.34 213.47 260 20 304.00 6.72 134.48

400 25 243.20 6.24 156.05 645 85 35.76 3.29 280.05 290 35 173.71 5.58 195.29 405 145 41.93 3.47 503.75

430 30 202.67 5.87 176.22 0 -645 0.00 0.00 0.00 325 35 173.71 5.58 195.29 0 -405 0.00 0.00 0.00

447 17 357.65 7.10 120.67 0 0 0.00 0.00 0.00 365 40 152.00 5.34 213.47 0 0 0.00 0.00 0.00

465 18 337.78 6.96 125.36 0 0 0.00 0.00 0.00 390 25 243.20 6.24 156.05 0 0 0.00 0.00 0.00

495 30 202.67 5.87 176.22 0 0 0.00 0.00 0.00 0 -390 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 -495 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

Sum 2202.39 Sum 1935.67 Sum 1852.06 Sum 1482.16



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KM 1+100 LHS NMC= KM 1+200 CL NMC= KM 1+300 RHS NMC= KM 1+400 LHS NMC=

Penetration

Depth (mm)

Thickness, t


Depth (mm)

Thickness, t


Depth (mm)

Thickness, t


Depth (mm)

Thickness, t


0 0 0.00 0 0 0 0.00 0 0 0 0.00 0 0 0 0.00 0

70 70 43.43 3.51 246.05 60 60 50.67 3.70 222.02 145 145 20.97 2.76 399.82 50 50 60.80 3.93 196.61

100 30 101.33 4.66 139.86 110 50 60.80 3.93 196.61 315 170 17.88 2.62 444.55 65 15 202.67 5.87 88.11

130 30 202.67 5.87 176.22 155 45 67.56 4.07 183.27 615 300 10.13 2.16 649.19 105 40 76.00 4.24 169.43

195 65 93.54 4.54 295.06 240 85 35.76 3.29 280.05 0 -615 0.00 0.00 0.00 470 365 16.66 2.55 932.17

220 25 243.20 6.24 156.05 295 55 110.55 4.80 263.96 0 0 0.00 0.00 0.00 570 100 30.40 3.12 312.10

240 20 304.00 6.72 134.48 330 35 173.71 5.58 195.29 0 0 0.00 0.00 0.00 695 125 24.32 2.90 362.16

250 10 608.00 8.47 84.72 370 40 152.00 5.34 213.47 0 0 0.00 0.00 0.00 0 -695 0.00 0.00 0.00

270 20 304.00 6.72 134.48 395 25 243.20 6.24 156.05 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 -270 0.00 0.00 0.00 415 20 304.00 6.72 134.48 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 450 35 173.71 5.58 195.29 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 460 10 608.00 8.47 84.72 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 470 10 608.00 8.47 84.72 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 -470 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00 0 0 0.00 0.00 0.00

Sum 1366.91 Sum 2209.93 Sum 1493.57 Sum 2060.58

CBRM 129.76 CBRM 103.95 CBRM 14.32 CBRM 26.06 1+500 CL NMC= KM 0+000 RHS 4 Hour Soaked KM 0+000 LHS 4 hour Soaked KM 0+200 RHS 4 hour Soaked

Penetration

Depth (mm)

Thickness, t


Depth (mm)

Thickness, t


Depth (mm)

Thickness, t


Depth (mm)

Thickness, t


0 0.00 0.00 0 0 0 0 0 0 0 0 0 0 0 0 0

240 240 12.67 2.33 559.46 185 185 8 2.02 373.30 145 145 10 2.19 317.34 185 185 8 2.02 373.30

330 90 33.78 3.23 290.93 220 35 43 3.51 123.02 200 55 28 3.02 166.29 318 133 11 2.25 299.58

410 80 38.00 3.36 268.96 270 50 61 3.93 196.61 270 70 43 3.51 246.05 460 142 11 2.20 312.95

495 85 35.76 3.29 280.05 305 35 87 4.43 155.00 340 70 43 3.51 246.05 568 108 14 2.41 260.75

570 75 40.53 3.44 257.63 342 37 82 4.35 160.85 420 80 38 3.36 268.96 0 -568 0 0.00 0.00

0 -570 0.00 0.00 0.00 370 28 109 4.77 133.58 495 75 41 3.44 257.63 0 0 0 0.00 0.00

0 0 0.00 0.00 0.00 435 65 94 4.54 295.06 545 50 61 3.93 196.61 0 0 0 0.00 0.00

0 0 0.00 0.00 0.00 485 50 122 4.95 247.71 585 40 76 4.24 169.43 0 0 0 0.00 0.00

0 0 0.00 0.00 0.00 0 -485 0 0.00 0.00 0 -585 0 0.00 0.00 0 0 0 0.00 0.00

Sum 1657.02 0 0 0.00 0.00 0.00 0 0 0 0.00 0.00 0 0 0 0.00 0.00CBRM 24.57 Sum 1685.14 Sum 1868.36 Sum 1246.59

CBRM 41.95 CBRM 32.58 CBRM 10.57 KM 0+200 CL 4 hour Soaked KM 0+600 CL 4 hour Soaked KM 1+300 RHS 4 hour Soaked KM 1+400 RHS 4Hrs Soaked

Penetration

Depth (mm)

Thickness, t

(mm)CBR (%) CBR

Pt x CBR

P Penetration

Depth (mm)

Thickness, t

(mm)CBR (%) CBR

Pt x CBR

P Penetration

Depth (mm)

Thickness, t

(mm)CBR (%) CBR

Pt x CBR

P Penetration

Depth (mm)

Thickness, t

(mm)CBR (%) CBR

Pt x CBR

P

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

220 220 7 1.90 419.02 90 90 34 3.23 290.93 120 120 13 2.33 279.73 100 100 3 1.45 144.86

290 70 22 2.79 195.29 110 20 304 6.72 134.48 150 30 51 3.70 111.01 140 40 8 1.97 78.64

360 70 22 2.79 195.29 120 10 608 8.47 84.72 195 45 68 4.07 183.27 160 20 15 2.48 49.54

435 75 20 2.73 204.48 125 5 1216 10.67 53.37 230 35 87 4.43 155.00 210 50 6 1.83 91.26

480 45 34 3.23 145.46 135 10 608 8.47 84.72 265 35 87 4.43 155.00 270 60 5 1.72 103.05

510 30 51 3.70 111.01 142 7 869 9.54 66.79 305 40 152 5.34 213.47 350 80 4 1.56 124.84

545 35 43 3.51 123.02 150 8 760 9.13 73.01 355 50 122 4.95 247.71 370 20 15 2.48 49.54

0 -545 0 0.00 0.00 270 120 51 3.70 444.04 390 35 174 5.58 195.29 410 40 8 1.97 78.64

0 0 0 0.00 0.00 440 170 36 3.29 560.10 420 30 203 5.87 176.22 430 20 15 2.48 49.54

0 0 0 0.00 0.00 540 100 61 3.93 393.22 455 35 174 5.58 195.29 450 20 15 2.48 49.54

0 0 0 0.00 0.00 0 -540 0 0.00 0.00 480 25 243 6.24 156.05 470 20 15 2.48 49.54

0 0 0 0.00 0.00 0 0 0 0.00 0.00 505 25 243 6.24 156.05 510 40 8 1.97 78.64

0 0 0 0.00 0.00 0 0 0 0.00 0.00 540 35 174 5.58 195.29 520 10 30 3.12 31.21

0 0 0 0.00 0.00 0 0 0 0.00 0.00 570 30 203 5.87 176.22 530 10 30 3.12 31.21

0 0 0 0.00 0.00 0 0 0 0.00 0.00 0 -570 0 0.00 0.00 540 10 30 3.12 31.21

0 0 0 0.00 0.00 0 0 0 0.00 0.00 0 0 0 0.00 0.00 0 -540 0 0.00 0.00

Sum 1393.58 Sum 2185.36 Sum 2595.60 Sum 1041.29



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The typical sieve analysis results of the coarse aggregate are presented in Table 5.5.1 and the corresponding

figure, while those of the fine aggregate are shown in Tables 5.5.2 and 5.5.3.

Table 5.5.4 and the corresponding figure are a summary of the typical characteristics of the coarse aggregates.

It can be noted that all the material tested indicates appreciable mechanical stability.

Table 5.5.1 Lab Sieve Analysis Results of Coarse Aggregate for Isiolo Airport – Runway


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Table 5.5.2 Lab Sieve Analysis Results of FineAggregate for Isiolo Airport - Runway

Sample time

(gm)

(gm)

(gm) (gm)

(gm) (%)

(gm) (%)

0.212 48.6 8.1 8.2 0

20 2.2

94.4

74.1

0.6

0.3

0.425

5



SIEVE ANALYSIS


176

10

0.8

95.2 15.9

4.8

2

1

6.3 8.8 1.5

566.4




Sample source

Sample N° :

36

100

60 100

Fine percent 687.2

96.7

100.0

1.1

95.2

Min(%) Max (%)

Acceptance Criteria

94.4

8

Acceptance Criteria

100

4.5

0.15

3.9

23.2 3.9 4.3

GRADING CURVE

13.4

6.6

26.8

154

23.2

48.4

16.380.8 13.5

111.8 100

25.7

89.9

5 70

97.8

89 100

10015

29.8


Fine mass

Sieve size (mm)

24-Feb-11

600

Test date:

Pan mass



ARCHERS POST SAND

Cumulative passed

percentage (%)

RUIRI

600

Sample Date

0.0

18.6

2.1

586.4

0

12.40.075 2.3 40

91

30

100

100

15

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

Pass

ing

(%)

Sieves (mm)


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Table 5.5.3 Fineness Modulus of Fine Aggregate for Isiolo Airport - Runway

Sample Class Fine Aggregate

(gm)

(gm)

(gm) (gm)

(gm) (%)

(gm) (%)

89

30

100

100

55

0.075 8.7

0.0

5.0

3.1

500

0

15.4


Fine mass

Sieve size (mm)

22-Feb-11

500

Test date:

Pan mass



QUARRY DUST-0.6mm

Cumulative passed

percentage (%)

RUIRI

600

Sample Date

0

4.8

161

52.6

43.3

24.7

16.317.2 3.4

24.8 80

10.5

55.8

5 70

100.0

89 100

10015

19.8

0.15 0

8.7

9.5 1.9 11.7

GRADING CURVE

15

100

60 100

Fine percent 687.2

99.0

100.0

1.0

92.6

Min(%) Max (%)

Acceptance Criteria

88.0

9

Acceptance Criteria

100

32.2



SIEVE ANALYSIS


176

10

4.6

103 20.6

22.8

2

1

6.3 32.2 6.4

440.2




Sample source

Sample N° :

20

0.212 13.4 2.7 13.6 3

14 0.0

88.0

35.2

0.6

0.3

0.425

5

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

Passing (%)

Sieves (mm)


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Table 5.5.4 Lab Sieve Analysis Results of CRS for Isiolo Airport - Runway

Table 5.5.5 is a summary of the strength and quality test results of the aggregates from Kiwira Quarry which is

about 14.40km from the airport.

The results show that all the stone quarries tested are of high quality with very high strengths, which is

characteristic of the Geomaterials within that region.


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Table 5.5.5 Summary of Stone Quarries Materials Tests Results for Isiolo Airport in Isiolo

KITHIMA QUARRY

1 14.34 Not>30% Not>30% Qualifies

2 14% Not>30% Not>40% Qualifies

3 388KN Not<100% Not<100% Not<75% Qualifies

4 0.40% Not>12% Not>9% Not>12% Qualifies

0.27% Not>3% Not>3% Not>3% Qualifies

# RemarksTESTED PARAMETERS

Aggregate Crushing Value (ACV)

Los Angeles Abrasion test (LAA)

Not>30%

Not>45%

Crushed Aggregate

base course

Asphalt Concrete

Surface Coarse

Asphalt Treated

Base Course

SPECIFICATIONS REQUIREMENTSTEST VALUE

Ten Percent Fines (TFV)

Soundness of Aggreg. By Sodium Sulphate Soln

Specific Gravity & Water Absorption - Coarse Aggregates

5.6 Summary of Bearing Capacity and Shearing Strength Parameters

A summary of the bearing capacity and shear strength parameters determined from in-situ tests is given in

Table 5.6.1, whilst the graphical characteristics of the CBR Mean against the chainage tested are depicted in

Fig. 5.6.1 and 5.6.2.

Table 5.6.2 shows the results of the cement stabilized material, while Fig. 5.6.3 shows the same for the

cement-geogrids stabilized materials.

In both cases the effect of chemical stabilization (treatment) can be appreciated. With the inclusion of the

Geogrids, the properties of the OPMC materials are enhanced. From Table 5.6.3, it can be inferred that the

UCS values has been improved by 20% for pozzolanic and power plus cement-geogrid stabilized materials;

PowerMax – Geogrid stabilized OPMC shows improvement values of 60%. [Note that all the results are 3%

cement stabilized and the curing modes 3 days soak].


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Table 5.6.1 Summary of Bearing Capacity and Shearing Strength Parameters for Isiolo Airport

(MPa)

1 16 Hrs Soaked KM 1+400 RHS 1.00 0.02 0.50 0.04 822 21192 210

2 4 Hour Soaked KM 0+000 RHS 41.95 1.01 20.70 1.62 3396 2095 7389

3 4 hour Soaked KM 0+000 LHS 32.58 0.79 16.07 1.26 3085 2450 5959

4 4 hour Soaked KM 0+200 RHS 10.57 0.26 5.22 0.41 2011 4923 2123

5 4 hour Soaked KM 0+200 CL 16.72 0.40 8.25 0.65 2394 3705 3269

6 4 hour Soaked KM 0+600 CL 66.28 1.60 32.70 2.56 4041 1577 10676

7 4 hour Soaked KM 1+300 RHS 94.43 2.28 46.59 3.65 4622 1267 13982

8 4Hrs Soaked KM 1+400 RHS 7.17 0.17 3.54 0.28 1736 6263 1462

9 Unsoaked KM 1+400 RHS 10.45 0.25 5.16 0.40 2003 4957 2101

10 KM 0+000 CL 56.87 1.37 28.06 2.20 3812 1734 9468

11 KM 0+050 LHS 31.75 0.77 15.66 1.23 3055 2490 5826

12 KM 0+100 CL 69.44 1.68 34.26 2.68 4113 1533 11067

13 KM 0+120 LHS 38.93 0.94 19.21 1.50 3301 2194 6940

14 KM 0+140 RHS 37.12 0.90 18.32 1.43 3242 2260 6666

15 KM 0+170 RHS 72.73 1.76 35.88 2.81 4186 1489 11467

16 KM 0+200 LHS 59.57 1.44 29.39 2.30 3880 1685 9822

17 KM 0+220 CL 84.66 2.04 41.77 3.27 4434 1355 12872

18 KM 0+260 RHS 18.32 0.44 9.04 0.71 2479 3501 3558

19 KM 0+300 CL 64.32 1.55 31.73 2.49 3995 1607 10430

20 KM 0+330 RHS 35.13 0.85 17.34 1.36 3175 2338 6360

21 KM 0+360 CL 84.10 2.03 41.49 3.25 4423 1361 12808

22 KM 0+390 RHS 59.32 1.43 29.27 2.29 3874 1690 9789

23 KM 0+400 LHS 40.07 0.97 19.77 1.55 3337 2155 7111

24 KM 0+450 CL 92.30 2.23 45.54 3.57 4582 1285 13742

25 KM 0+480 RHS 22.97 0.55 11.33 0.89 2701 3043 4372

26 KM 0+500 LHS 44.06 1.06 21.74 1.70 3460 2032 7697

27 KM 0+540 CL 110.57 2.67 54.55 4.27 4908 1149 15784

31 KM 0+570 LHS 32.26 0.78 15.91 1.25 3073 2465 5907

32 KM 0+600 CL 60.28 1.46 29.74 2.33 3898 1673 9914

33 KM 0+630 CL 157.59 3.81 77.75 6.09 5615 922 21461

34 KM 0+660 LHS 110.57 2.67 54.55 4.27 4908 1149 15784

35 KM 0+700 RHS 88.08 2.13 43.46 3.40 4502 1322 13264

36 KM 0+740 LHS 17.40 0.42 8.58 0.67 2430 3615 3391

37 KM 0+770 RHS 28.51 0.69 14.07 1.10 2932 2662 5302

38 KM 0+800 LHS 27.03 0.65 13.34 1.04 2874 2751 5058

39 KM 0+860 RHS 19.86 0.48 9.80 0.77 2556 3330 3831

40 KM 0+900 CL 107.10 2.59 52.84 4.14 4849 1172 15397

41 KM 0+940 RHS 8.62 0.21 4.25 0.33 1861 5588 1746

42 KM 0+970 CL 152.58 3.69 75.28 5.90 5547 941 20790

43 KM 1+000 RHS 49.01 1.18 24.18 1.89 3603 1902 8401

44 KM 1+060 CL 133.40 3.22 65.82 5.16 5271 1022 18397

45 KM 1+100 LHS 129.76 3.13 64.02 5.01 5216 1040 17968

46 KM 1+140 CL 74.94 1.81 36.98 2.90 4234 1462 11734

47 KM 1+200 CL 103.95 2.51 51.29 4.02 4794 1193 15047

48 KM 1+300 RHS 14.32 0.35 7.07 0.55 2257 4078 2830

49 KM 1+400 RHS 26.06 0.63 12.86 1.01 2834 2814 4897

50 KM 1+500 CL 24.57 0.59 12.12 0.95 2771 2919 4646

M r cor (MPa)Emax (MPa)

Lo

ca

tio

n

Surface Type Chainage CBRM (%) UCS qu (MPa) N-Value Emax / qmaxmaxq


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Fig. 5.6.1 CBR Mean values at Chainages on Isiolo Airport Runway

Fig. 5.6.1 CBR Mean SOAK values at Chainages on Isiolo Airport Runway


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The Bearing Capacity test results are presented in the preceding sections 5.3 and 5.5 of this Report.


The importance of studying consolidation properties was considered for three main reasons:

1. To analyze the effect of chemical-mechanical stabilization on consolidation properties since

consolidation is one of the methods commonly applied for ground improvement.

2. To evaluate whether or not and to what extent water infiltration or groundwater seepage would

affect the consolidation properties of the chemically/mechanically stabilized Geomaterials

associated with settlement and reduction in magnitude of shear stress as well as resistance to

deformation.

3. To evaluate whether further secondary consolidation is likely to occur to a detrimental extent that

would cause settlement particularly for the lower layers under surcharge and dynamic traffic loading.

In general, the following observations can be made from Tables 5.8.1 to 5.8.3.

(a) Chemical stabilization enhances the vital consolidation parameters such as CSR, CSR and .

(b) The mechanical stabilization further enhances the vital consolidation parameters to higher values as

compared to chemical stabilization only, as can be seen in table 5.8.3

(c) The degree of influence of the chemical stabilization on the vital consolidation parameters depends

on the type of Geomaterials


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Table 5.8.1 Summary of Consolidation Stress Parameters Derived from In-situ Tests

(MPa) (MPa) (MPa) Average (MPa) (MPa) (MPa) (MPa)

1 KM 1+400 RHS 1.00 0.02 0.50 0.01 0.04 0.04 27.688 29.375 46.912 1.283 15.600 0.333 1.015 0.915 0.432 0.384 0.05 0.01 0.04 0.052 KM 0+000 RHS 41.95 1.01 20.70 0.51 1.62 1.45 28.187 29.925 48.698 1.295 15.891 0.326 1.008 0.951 0.418 0.378 2.01 0.39 1.62 2.273 KM 0+000 LHS 32.58 0.79 16.07 0.39 1.26 1.13 28.073 29.799 48.289 1.292 15.825 0.328 1.010 0.943 0.421 0.380 1.56 0.30 1.26 1.764 KM 0+200 RHS 10.57 0.26 5.22 0.13 0.41 0.37 27.805 29.504 47.329 1.286 15.668 0.331 1.013 0.924 0.428 0.383 0.51 0.10 0.41 0.585 KM 0+200 CL 16.72 0.40 8.25 0.20 0.65 0.58 27.880 29.586 47.598 1.288 15.712 0.330 1.012 0.929 0.426 0.382 0.80 0.16 0.65 0.916 KM 0+600 CL 66.28 1.60 32.70 0.80 2.56 2.26 28.483 30.251 49.760 1.302 16.064 0.323 1.004 0.973 0.410 0.375 3.16 0.60 2.56 3.577 KM 1+300 RHS 94.43 2.28 46.59 1.14 3.65 3.18 28.826 30.629 50.988 1.311 16.264 0.319 1.000 0.998 0.401 0.371 4.49 0.84 3.65 5.059 KM 1+400 RHS 7.17 0.17 3.54 0.09 0.28 0.25 27.764 29.458 47.181 1.285 15.644 0.332 1.014 0.921 0.430 0.383 0.35 0.07 0.28 0.39

10 KM 1+400 RHS 10.45 0.25 5.16 0.13 0.40 0.37 27.803 29.502 47.324 1.286 15.667 0.331 1.013 0.924 0.428 0.383 0.50 0.10 0.40 0.5711 KM 0+000 CL 56.87 1.37 28.06 0.69 2.20 1.95 28.368 30.125 49.349 1.300 15.997 0.324 1.006 0.965 0.413 0.376 2.72 0.52 2.20 3.0712 KM 0+050 LHS 31.75 0.77 15.66 0.38 1.23 1.10 28.063 29.788 48.253 1.292 15.819 0.328 1.010 0.942 0.421 0.380 1.52 0.30 1.23 1.7213 KM 0+100 CL 69.44 1.68 34.26 0.84 2.68 2.36 28.521 30.293 49.898 1.303 16.086 0.322 1.004 0.976 0.409 0.374 3.31 0.63 2.68 3.7314 KM 0+120 LHS 38.93 0.94 19.21 0.47 1.50 1.34 28.150 29.884 48.567 1.294 15.870 0.327 1.009 0.949 0.419 0.379 1.87 0.36 1.50 2.1115 KM 0+140 RHS 37.12 0.90 18.32 0.45 1.43 1.28 28.128 29.860 48.488 1.294 15.857 0.327 1.009 0.947 0.419 0.379 1.78 0.34 1.43 2.0116 KM 0+170 RHS 72.73 1.76 35.88 0.88 2.81 2.47 28.561 30.338 50.041 1.304 16.110 0.322 1.003 0.979 0.408 0.374 3.47 0.66 2.81 3.9117 KM 0+200 LHS 59.57 1.44 29.39 0.72 2.30 2.04 28.401 30.161 49.467 1.300 16.016 0.324 1.005 0.967 0.412 0.376 2.85 0.54 2.30 3.2118 KM 0+220 CL 84.66 2.04 41.77 1.02 3.27 2.86 28.707 30.498 50.562 1.308 16.194 0.320 1.001 0.989 0.404 0.372 4.03 0.76 3.27 4.5419 KM 0+260 RHS 18.32 0.44 9.04 0.22 0.71 0.64 27.899 29.608 47.668 1.288 15.723 0.330 1.012 0.930 0.426 0.382 0.88 0.17 0.71 1.0020 KM 0+300 CL 64.32 1.55 31.73 0.78 2.49 2.19 28.459 30.225 49.674 1.302 16.050 0.323 1.005 0.971 0.411 0.375 3.07 0.59 2.49 3.4621 KM 0+330 RHS 35.13 0.85 17.34 0.42 1.36 1.21 28.104 29.833 48.401 1.293 15.843 0.327 1.009 0.945 0.420 0.379 1.68 0.33 1.36 1.9022 KM 0+360 CL 84.10 2.03 41.49 1.02 3.25 2.84 28.700 30.490 50.537 1.308 16.190 0.320 1.002 0.989 0.404 0.372 4.00 0.75 3.25 4.5123 KM 0+390 RHS 59.32 1.43 29.27 0.72 2.29 2.03 28.398 30.158 49.456 1.300 16.014 0.324 1.005 0.967 0.412 0.376 2.83 0.54 2.29 3.2024 KM 0+400 LHS 40.07 0.97 19.77 0.48 1.55 1.38 28.164 29.900 48.616 1.295 15.878 0.327 1.008 0.950 0.418 0.379 1.92 0.37 1.55 2.1725 KM 0+450 CL 92.30 2.23 45.54 1.11 3.57 3.11 28.800 30.600 50.895 1.310 16.249 0.319 1.000 0.996 0.401 0.371 4.39 0.82 3.57 4.9426 KM 0+480 RHS 22.97 0.55 11.33 0.28 0.89 0.80 27.956 29.670 47.870 1.289 15.756 0.329 1.011 0.935 0.424 0.381 1.10 0.22 0.89 1.2527 KM 0+500 LHS 44.06 1.06 21.74 0.53 1.70 1.52 28.213 29.953 48.790 1.296 15.906 0.326 1.008 0.953 0.417 0.378 2.11 0.41 1.70 2.3828 KM 0+540 CL 110.57 2.67 54.55 1.34 4.27 3.69 29.022 30.845 51.692 1.315 16.378 0.317 0.998 1.012 0.396 0.369 5.24 0.97 4.27 5.8929 KM 0+570 LHS 32.26 0.78 15.91 0.39 1.25 1.12 28.069 29.795 48.275 1.292 15.822 0.328 1.010 0.943 0.421 0.380 1.55 0.30 1.25 1.7530 KM 0+600 CL 60.28 1.46 29.74 0.73 2.33 2.06 28.410 30.171 49.498 1.301 16.021 0.324 1.005 0.968 0.412 0.376 2.88 0.55 2.33 3.2531 KM 0+630 CL 157.59 3.81 77.75 1.90 6.09 5.15 29.594 31.476 53.743 1.328 16.712 0.311 0.991 1.054 0.381 0.363 7.43 1.34 6.09 8.3232 KM 0+660 LHS 24.57 0.59 12.12 0.30 0.95 0.85 27.975 29.692 47.940 1.290 15.768 0.329 1.011 0.936 0.424 0.381 1.18 0.23 0.95 1.3333 KM 0+700 RHS 88.08 2.13 43.46 1.06 3.40 2.97 28.748 30.544 50.711 1.309 16.219 0.320 1.001 0.992 0.403 0.372 4.19 0.79 3.40 4.7234 KM 0+740 LHS 17.40 0.42 8.58 0.21 0.67 0.61 27.888 29.595 47.627 1.288 15.717 0.330 1.012 0.930 0.426 0.382 0.84 0.16 0.67 0.9535 KM 0+770 RHS 28.51 0.69 14.07 0.34 1.10 0.99 28.023 29.744 48.112 1.291 15.796 0.328 1.010 0.939 0.422 0.380 1.37 0.27 1.10 1.5536 KM 0+800 LHS 27.03 0.65 13.34 0.33 1.04 0.94 28.005 29.725 48.047 1.291 15.785 0.329 1.010 0.938 0.423 0.380 1.30 0.25 1.04 1.4737 KM 0+860 RHS 19.86 0.48 9.80 0.24 0.77 0.69 27.918 29.628 47.735 1.289 15.734 0.330 1.012 0.932 0.425 0.381 0.95 0.19 0.77 1.0838 KM 0+900 CL 107.10 2.59 52.84 1.29 4.14 3.58 28.980 30.799 51.540 1.314 16.354 0.317 0.998 1.009 0.397 0.369 5.08 0.94 4.14 5.7139 KM 0+940 RHS 8.62 0.21 4.25 0.10 0.33 0.30 27.781 29.478 47.244 1.285 15.654 0.331 1.014 0.922 0.429 0.383 0.41 0.08 0.33 0.4740 KM 0+970 CL 152.58 3.69 75.28 1.84 5.90 5.00 29.533 31.409 53.525 1.327 16.677 0.312 0.992 1.050 0.382 0.363 7.20 1.30 5.90 8.0641 KM 1+000 RHS 49.01 1.18 24.18 0.59 1.89 1.68 28.273 30.020 49.007 1.297 15.941 0.325 1.007 0.958 0.416 0.377 2.35 0.45 1.89 2.6542 KM 1+060 CL 133.40 3.22 65.82 1.61 5.16 4.41 29.300 31.152 52.688 1.321 16.541 0.314 0.995 1.033 0.388 0.366 6.31 1.15 5.16 7.0843 KM 1+100 LHS 129.76 3.13 64.02 1.57 5.01 4.29 29.256 31.103 52.529 1.320 16.515 0.314 0.995 1.029 0.390 0.366 6.14 1.12 5.01 6.8944 KM 1+140 CL 74.94 1.81 36.98 0.91 2.90 2.54 28.588 30.367 50.138 1.305 16.125 0.322 1.003 0.981 0.407 0.374 3.57 0.68 2.90 4.0245 KM 1+200 CL 103.95 2.51 51.29 1.26 4.02 3.48 28.942 30.757 51.403 1.313 16.331 0.318 0.999 1.006 0.398 0.370 4.94 0.92 4.02 5.5546 KM 1+300 RHS 14.32 0.35 7.07 0.17 0.55 0.50 27.851 29.554 47.493 1.287 15.695 0.330 1.013 0.927 0.427 0.382 0.69 0.14 0.55 0.7847 KM 1+400 RHS 26.06 0.63 12.86 0.31 1.01 0.91 27.993 29.712 48.005 1.290 15.778 0.329 1.011 0.937 0.423 0.381 1.25 0.24 1.01 1.4148 KM 1+500 CL 24.57 0.59 12.12 0.30 0.95 0.85 27.975 29.692 47.940 1.290 15.768 0.329 1.011 0.936 0.424 0.381 1.18 0.23 0.95 1.33

Location CSRSerial

No.CBRM(%)

UCS qu

(MPa)N-Value

Cu ɸ'A ɸ'U

Upper

limit

qC pC’

maxq'

fPCSR CSR/ 1

CSR OKCK

1

ac

1

rc

Table 5.8.2 Summary of Consolidation Stress Parameters Derived from Laboratory UCSTests of Cement

Stabilized OPMC-[Chemical stabilization]

MIX

Sample (MPa) (MPa) (MPa) (MPa) (MPa) (MPa)

1 Pozzolanic 0.66 0.33 1.06 48.060 1.291 15.787 0.328 1.010 0.938 0.423 0.380 1.31 0.26 1.06 1.48

3 PowerMax 0.6 0.30 0.96 47.952 1.290 15.770 0.329 1.011 0.936 0.424 0.381 1.19 0.23 0.96 1.35

4 PowerPlus 0.96 0.48 1.54 48.602 1.295 15.875 0.327 1.008 0.949 0.419 0.379 1.90 0.37 1.54 2.15

Note that the cement contect is 3% and the curing mode 3days soak

qC pC’

Serial No. UCS qu (MPa)Cu

CSRmaxq

maxq

CSR CSR/1

CSR OKCK

1

ac

1

rc


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Table 5.8.3 Summary of Consolidation Stress Parameters Derived from Laboratory UCS test of Cement-

Geogrid Stabilized OPMC-[Chemical - Mechanical stabilization]

MIX

Sample (MPa) (MPa) (MPa) (MPa) (MPa) (MPa)

1 Pozzolanic 0.792 0.40 1.27 48.299 1.292 15.826 0.328 1.010 0.943 0.421 0.380 1.57 0.31 1.27 1.78

0 PowerMax 0.962 0.48 1.54 48.606 1.295 15.876 0.327 1.008 0.949 0.419 0.379 1.91 0.37 1.54 2.15

4 PowerPlus 1.148 0.57 1.84 48.942 1.297 15.931 0.326 1.007 0.956 0.416 0.377 2.27 0.44 1.84 2.57

Note that the cement contect is 3% and the curing mode 3days soak

pC’qC

Serial No. UCS qu (MPa)Cu

CSR

maxq

CSR CSR/1

CSR OKCK

1

ac

1

rc


A summary of the shear parameters derived from in-situ tests is given in Table 5.9.1.

This Table presents the results computed by adopting Equations 4.18 in sub-section 4.3.1 and 4.33 ~ 4.38 in

sub-section 4.5.1 of Chapter 4.

Table 5.9.1 Summary of Shear Stress Parameters Derived from In-situ Tests

(MPa) (MPa) (MPa) Average (MPa) (MPa)

KM 1+400 RHS 1.00 0.02 0.01 0.04 0.04 27.688 0.05 0.01 1.1230 6 822 274 3.39 0.380 0.100 0.1656 21192KM 0+000 RHS 41.95 1.01 0.51 1.62 1.45 28.187 2.01 0.39 1.1440 252 3396 1132 34.25 0.563 0.209 0.3356 2095KM 0+000 LHS 32.58 0.79 0.39 1.26 1.13 28.073 1.56 0.30 1.1392 196 3085 1028 29.29 0.521 0.184 0.2975 2450KM 0+200 RHS 10.57 0.26 0.13 0.41 0.37 27.805 0.51 0.10 1.1279 63 2011 670 14.57 0.422 0.125 0.2060 4923KM 0+200 CL 16.72 0.40 0.20 0.65 0.58 27.880 0.80 0.16 1.1310 100 2394 798 19.37 0.450 0.142 0.2318 3705KM 0+600 CL 66.28 1.60 0.80 2.56 2.26 28.483 3.16 0.60 1.1565 398 4041 1347 45.49 0.673 0.274 0.4317 1577KM 1+300 RHS 94.43 2.28 1.14 3.65 3.18 28.826 4.49 0.84 1.1709 567 4622 1541 56.65 0.799 0.348 0.5373 1267KM 1+400 RHS 7.17 0.17 0.09 0.28 0.25 27.764 0.35 0.07 1.1261 43 1736 579 11.46 0.407 0.116 0.1916 6263KM 1+400 RHS 10.45 0.25 0.13 0.40 0.37 27.803 0.50 0.10 1.1278 63 2003 668 14.47 0.422 0.125 0.2055 4957KM 0+000 CL 56.87 1.37 0.69 2.20 1.95 28.368 2.72 0.52 1.1516 341 3812 1271 41.37 0.631 0.249 0.3950 1734KM 0+050 LHS 31.75 0.77 0.38 1.23 1.10 28.063 1.52 0.30 1.1387 191 3055 1018 28.82 0.518 0.182 0.2941 2490KM 0+100 CL 69.44 1.68 0.84 2.68 2.36 28.521 3.31 0.63 1.1581 417 4113 1371 46.82 0.687 0.282 0.4438 1533KM 0+120 LHS 38.93 0.94 0.47 1.50 1.34 28.150 1.87 0.36 1.1424 234 3301 1100 32.70 0.550 0.201 0.3234 2194KM 0+140 RHS 37.12 0.90 0.45 1.43 1.28 28.128 1.78 0.34 1.1415 223 3242 1081 31.76 0.542 0.196 0.3161 2260KM 0+170 RHS 72.73 1.76 0.88 2.81 2.47 28.561 3.47 0.66 1.1598 437 4186 1395 48.18 0.702 0.291 0.4564 1489KM 0+200 LHS 59.57 1.44 0.72 2.30 2.04 28.401 2.85 0.54 1.1530 358 3880 1293 42.58 0.643 0.256 0.4056 1685KM 0+220 CL 84.66 2.04 1.02 3.27 2.86 28.707 4.03 0.76 1.1659 508 4434 1478 52.94 0.755 0.322 0.5013 1355KM 0+260 RHS 18.32 0.44 0.22 0.71 0.64 27.899 0.88 0.17 1.1318 110 2479 826 20.50 0.457 0.146 0.2386 3501KM 0+300 CL 64.32 1.55 0.78 2.49 2.19 28.459 3.07 0.59 1.1555 386 3995 1332 44.65 0.664 0.268 0.4241 1607KM 0+330 RHS 35.13 0.85 0.42 1.36 1.21 28.104 1.68 0.33 1.1405 211 3175 1058 30.69 0.533 0.191 0.3080 2338KM 0+360 CL 84.10 2.03 1.02 3.25 2.84 28.700 4.00 0.75 1.1656 505 4423 1474 52.72 0.753 0.321 0.4992 1361KM 0+390 RHS 59.32 1.43 0.72 2.29 2.03 28.398 2.83 0.54 1.1529 356 3874 1291 42.46 0.641 0.255 0.4046 1690KM 0+400 LHS 40.07 0.97 0.48 1.55 1.38 28.164 1.92 0.37 1.1430 241 3337 1112 33.30 0.555 0.204 0.3280 2155KM 0+450 CL 92.30 2.23 1.11 3.57 3.11 28.800 4.39 0.82 1.1698 554 4582 1527 55.85 0.790 0.343 0.5295 1285KM 0+480 RHS 22.97 0.55 0.28 0.89 0.80 27.956 1.10 0.22 1.1342 138 2701 900 23.58 0.478 0.158 0.2579 3043KM 0+500 LHS 44.06 1.06 0.53 1.70 1.52 28.213 2.11 0.41 1.1451 264 3460 1153 35.31 0.573 0.214 0.3441 2032KM 0+540 CL 110.57 2.67 1.34 4.27 3.69 29.022 5.24 0.97 1.1792 664 4908 1636 62.47 0.872 0.391 0.5950 1149KM 0+570 LHS 32.26 0.78 0.39 1.25 1.12 28.069 1.55 0.30 1.1390 194 3073 1024 29.11 0.520 0.183 0.2962 2465KM 0+600 CL 60.28 1.46 0.73 2.33 2.06 28.410 2.88 0.55 1.1534 362 3898 1299 42.89 0.646 0.258 0.4084 1673KM 0+630 CL 157.59 3.81 1.90 6.09 5.15 29.594 7.43 1.34 1.2034 946 5615 1872 77.82 1.083 0.516 0.7509 922KM 0+660 LHS 24.57 0.59 0.30 0.95 0.85 27.975 1.18 0.23 1.1351 147 2771 924 24.58 0.485 0.163 0.2645 2919KM 0+700 RHS 88.08 2.13 1.06 3.40 2.97 28.748 4.19 0.79 1.1677 529 4502 1501 54.26 0.771 0.331 0.5140 1322KM 0+740 LHS 17.40 0.42 0.21 0.67 0.61 27.888 0.84 0.16 1.1314 104 2430 810 19.85 0.453 0.144 0.2347 3615KM 0+770 RHS 28.51 0.69 0.34 1.10 0.99 28.023 1.37 0.27 1.1371 171 2932 977 26.96 0.503 0.173 0.2808 2662KM 0+800 LHS 27.03 0.65 0.33 1.04 0.94 28.005 1.30 0.25 1.1363 162 2874 958 26.08 0.496 0.169 0.2747 2751KM 0+860 RHS 19.86 0.48 0.24 0.77 0.69 27.918 0.95 0.19 1.1326 119 2556 852 21.55 0.464 0.150 0.2450 3330KM 0+900 CL 107.10 2.59 1.29 4.14 3.58 28.980 5.08 0.94 1.1774 643 4849 1616 61.25 0.856 0.382 0.5827 1172KM 0+940 RHS 8.62 0.21 0.10 0.33 0.30 27.781 0.41 0.08 1.1269 52 1861 620 12.84 0.414 0.120 0.1978 5588KM 0+970 CL 152.58 3.69 1.84 5.90 5.00 29.533 7.20 1.30 1.2008 916 5547 1849 76.28 1.060 0.503 0.7352 941KM 1+000 RHS 49.01 1.18 0.59 1.89 1.68 28.273 2.35 0.45 1.1476 294 3603 1201 37.73 0.595 0.228 0.3639 1902KM 1+060 CL 133.40 3.22 1.61 5.16 4.41 29.300 6.31 1.15 1.1910 801 5271 1757 70.18 0.974 0.452 0.6730 1022KM 1+100 LHS 129.76 3.13 1.57 5.01 4.29 29.256 6.14 1.12 1.1891 779 5216 1739 68.99 0.958 0.442 0.6608 1040KM 1+140 CL 74.94 1.81 0.91 2.90 2.54 28.588 3.57 0.68 1.1609 450 4234 1411 49.09 0.712 0.297 0.4648 1462KM 1+200 CL 103.95 2.51 1.26 4.02 3.48 28.942 4.94 0.92 1.1758 624 4794 1598 60.13 0.842 0.374 0.5716 1193KM 1+300 RHS 14.32 0.35 0.17 0.55 0.50 27.851 0.69 0.14 1.1298 86 2257 752 17.60 0.439 0.135 0.2218 4078KM 1+400 RHS 26.06 0.63 0.31 1.01 0.91 27.993 1.25 0.24 1.1358 156 2834 945 25.50 0.492 0.167 0.2707 2814KM 1+500 CL 24.57 0.59 0.30 0.95 0.85 27.975 1.18 0.23 1.1351 147 2771 924 24.58 0.485 0.163 0.2645 2919

Emax

(MPa)

Gmax

(MPa)Chainage

(εa)max

(calculated)

(%)

(εa)50

(calculated)

(%)

(εa)ELS

(10-3) (%)

Emax /

qmax

Cu ɸ'A ΦELSUCS qu

(MPa)

CBRM

(%)

E50

(MPa)maxqSR

'

fP'

a

'

r


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The following observations can be made from the foregoing Table 5.9.1 and the corresponding Figures.

1) The laboratory test results indicate enhanced intrinsic shearing properties of the sub-base.

The intrinsic properties are further enhanced when geogrid is incorporated in the

pavement base layers.

2) The in-situ test results show that the shearing strength is immensely enhanced as a result

of the coupled effects of long term consolidation and cementetious agglomeration.

5.10 Modulus of Deformation, Elastic Modulus and Linear Elastic Range

A summary of the derived modulus of deformation, elastic and shear modulus and elastic limit strain, which is

defined as the range of linear elastic and recoverable behavior, given in Tables 5.10.1 and 5.10.2, were

computed by applying Equations 4.48 ~ 4.52.

The normalized relations are also presented in the same Tables.

Table 5.10.1 Summary of Modulus of Deformation Parameters from Lab Test Results

1 BCS subgrade 12 1074 357.85 5.23 0.38 0.102782 0.169885 13713

2 BP1 LMD gravel 347 3834 1278.04 41.76 0.63 0.250794 0.398410 1718

3 BP2 78 Tank Batt 389 4007 1335.55 44.87 0.67 0.269632 0.426033 1599

5 BP5 Murero 173 2946 982.10 27.17 0.50 0.174097 0.282299 2641

6 BP6 LMD Sandy 49 1818 606.02 12.36 0.41 0.118929 0.195580 5806

Spec

imen

MIXE50

(MPa)

Emax

(MPa)

Gmax

(MPa)ΦELS

(εa)max

(calculated)

(%)

(εa)50

(calculated) (%)

(εa)ELS

(10-3) (%)

Emax /

qmax

Table 5.10.2 Summary of Modulus of Deformation Parameters from In-situ Test Results

1 1+400 RHS 6 822 274.06

2 1+400 RHS 43 1736 578.51

3 1+400 RHS 63 2003 667.65

4 0+000 CL 341 3812 1270.77

5 0+050 LHS 191 3055 1018.25

6 0+100 CL 417 4113 1370.91

7 0+170 RHS 437 4186 1395.24

8 0+200 LHS 358 3880 1293.37

9 0+300 CL 386 3995 1331.60

10 0+400 RHS 241 3337 1112.47

11 0+500 LHS 264 3460 1153.31

12 0+600 CL 362 3898 1299.22

13 0+700 RHS 529 4502 1500.57

14 0+800 LHS 162 2874 957.85

15 0+900 CL 643 4849 1616.29

16 1+000 RHS 294 3603 1200.96

17 1+100 LHS 779 5216 1738.59

18 1+200 CL 624 4794 1598.11

19 1+300 RHS 86 2257 752.50

20 1+400 LHS 156 2834 944.70

21 1+500 CL 147 2771 923.73

Location Chainage Emax (MPa) Gmax (MPa)E50 (MPa)


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The results basically indicate that, for stiff Geomaterials such as the one tested above, the shearing strength

increases virtually directly proportionally to the deformation resistance.


The results of deformation properties and the linear elastic range are presented in Table 5.11.1 below.

The results basically indicate that as the shearing strength increases with the deformation resistance, the

linear elastic range is immensely enhanced.

Table 5.11.1 Summary of Modulus of Deformation Parameters from in-situ Test Results

1 1+400 RHS 3.39 0.38 0.100067 0.165596 21192

2 1+400 RHS 11.46 0.41 0.116451 0.191637 6263

3 1+400 RHS 14.47 0.42 0.125178 0.205511 4957

4 0+000 CL 41.37 0.63 0.248508 0.395033 1734

5 0+050 LHS 28.82 0.52 0.181752 0.294136 2490

6 0+100 CL 46.82 0.69 0.281891 0.443810 1533

7 0+170 RHS 48.18 0.70 0.290635 0.456390 1489

8 0+200 LHS 42.58 0.64 0.255684 0.405614 1685

9 0+300 CL 44.65 0.66 0.268294 0.424083 1607

10 0+400 RHS 33.30 0.56 0.203872 0.328043 2155

11 0+500 LHS 35.31 0.57 0.214470 0.344124 2032

12 0+600 CL 42.89 0.65 0.257576 0.408396 1673

13 0+700 RHS 54.26 0.77 0.331423 0.513981 1322

14 0+800 LHS 26.08 0.50 0.169214 0.274721 2751

15 0+900 CL 61.25 0.86 0.381952 0.582743 1172

16 1+000 RHS 37.73 0.60 0.227632 0.363946 1902

17 1+100 LHS 68.99 0.96 0.442167 0.660848 1040

18 1+200 CL 60.13 0.84 0.373607 0.571587 1193

19 1+300 RHS 17.60 0.44 0.135458 0.221796 4078

20 1+400 LHS 25.50 0.49 0.166648 0.270730 2814

21 1+500 CL 24.58 0.49 0.162676 0.264543 2919

Locati

onChainage ΦELS

(εa)ELS

(10-3) (%)

Emax /

qmax

(εa)max

(calculated)

(%)

(εa)50

(calculated) (%)

5.12 Summary of the effects of curing period on soil particle agglomeration and unconfined strength.

From the laboratory test results OPMC Stabilized + Geogrid samples yields UCS values of 3.32 after 3day cure

with 2% cement content [PowerPlus]. After extrapolation from the relation that is explained in chapter 4, the

following table gives the expected calculated properties after several days of curing.


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Table: 5.12.1 Effects of curing period on OPMC Level 3

Fig: 5.12.1 Graphical representation of the effects of Curing Period on the OPMC material

Effects of curing period on OPMC Level 3 & Geogrid, PowerPlus 2% for 3 days Cure/soak

1 24 2.28 4,621.72 95.00

3 72 3.31 5,327.08 138.06

7 168 5.51 6,463.93 229.68

14 336 11.09 8,431.71 462.23

28 672 26.11 11,673.06 1,087.98

56 1344 66.30 16,632.49 2,762.40

112 2688 173.09 23,951.49 7,212.12

Curing Periods,

CP[hours]UCS, qu

f [Mpa]Days Emax CBR [%]


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From the above it can be clearly stated that the UCS and Emax properties of the OPMC material increases with

time. For design purposes we have used UCS strengths as is at 3 days cure/soak; this is a reserve value since

from Table 5.12.1 we can infer that the strength will appreciate to greater values.

Table 5.12.2 Effects of curing period on Resulting, ER Composite Pavement

Effects of curing period on Resulting Er (composite pavement)

UCS, QurFCB

1 24 2.11 0.80 1,414.00 1,317.00 87.92 3 72 3.76 1.64 5,589.87 4,073.88 156.71 7 168 5.77 1.89 6,576.69 4,305.93 240.38

14 336 8.23 2.10 7,527.62 4,481.61 342.95 28 672 11.44 2.31 8,530.34 4,646.73 476.60 56 1344 15.59 2.52 9,595.18 4,802.78 649.52

112 2688 20.93 2.73 10,731.70 4,950.97 872.02 224 5376 27.77 2.94 11,949.16 5,092.26 1,157.02 448 10752 36.50 3.15 13,256.83 5,227.42 1,520.65

896 21504 47.59 3.36 14,664.18 5,357.11 1,983.08 1792 43008 61.67 3.57 16,181.03 5,481.88 2,569.43

Days Curing Periods, CP[hours]

UCS, qurFCA [Mpa] Emax ER

CA CBR [%]Emax ER


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Fig 5.12.2 Graphical presentation of the effects of curing on the Resultant Composite Pavement [Derived from

table 5.12.2]

The resultant pavement strength also appreciates with time as is in case 5.12.1.


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CHAPTER 6

6. APPLICATION OF TEST RESULTS


For purposes of quantifying the magnitude of change of the physical properties of the existing foundation

Geomaterials and their corresponding effects on the bearing capacity, strength, moduli of deformation, basic

parameters such as natural moisture content (win), Atterberg Limits (PI, LL, WL, & LS), Specific Gravity (Gs),

voids ratio (e), dry density ( d) and degree of saturation (Sir) were determined based on the standard soil

model expressions.

In soil mechanics, plasticity index is a function of the amount of clay present in a soil, while the Liquid Limit

and Plastic Limits individually are functions of both the amount and type of clay. High plasticity indices are

analogous to high water contents whose lubricating effect of the water films between adjacent soil particles

tends to reduce the mechanical stability, strength and deformation resistance.

The results from the Atterberg Limits will be used to mainly study the quantitative effects of moisture-suction

variations of the site soils based on Equations (4.1) ~ (4.6) presented in Chapter 4 of this Report.

6.2 Borehole Log Results

Borehole results are mainly analyzed from two paramount perspectives, namely Soil Classification and

Penetration Resistance.

Soil Classification

These results will mainly be used for purposes of coming up with a soils description that can convey sufficient

information to enable the designers and constructors to appreciate the nature and properties of the soils and

to anticipate the likely behavior and potential problems.

The results have been comprehensively analyzed with an aim to:

(1) Provide a systematic soil description for both a hand specimen and a stratum within a soil deposit

in order to, as much as possible, clearly define the nature of the soil in existence at the Project

Site.

(2) Determine values of soil classification parameters from laboratory tests including particle density,

grading, bulk density, moisture content and consistency limits.

(3) Utilize accordingly, the soil classification results extrapolatively in evaluating the geotechnical

engineering soundness of the design and construction of the foundation and any other

Geostructure within the Project.

(4) Apply the soil model to the determination of a range of parameters used in soil mechanics to

denote the state or condition of a soil.

Penetration Resistance

From the results obtained in the field in reference to the penetration resistance during drilling and dynamic

cone penetration, Equations (4.14) ~ (4.19) are utilized in determining the bearing capacity, and strength of

the Geomaterials and foundation ground tested.


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6.3 Dynamic Penetration Test Results

Results obtained from the Dynamic Cone Penetration testing have been versatile in utility whereby they

yielded various useful geotechnical engineering parameters that can be used for design and construction QC,

including bearing capacity, strength and deformation resistance.

The DCP test results are utilized as the main parameters in Equations (4.1) ~ (4.44).


The purpose of undertaking aggregate tests was to confirm their quality and strength accordingly.

The test results are applied in analyzing the contribution of the aggregate particles to the mechanical stability,

bearing capacity, strength and deformation resistance of the composite pavement structure.

6.5 Laboratory Test Results

The utilization of laboratory test results has been discussed in the preceding sub-section 6.1.


The bearing capacity results were basically derived from the Dynamic Cone Penetration Tests. In this study, the

results are applied as stipulated below.

(a) Overall structural analysis of the composite structure

(b) Comparison of CBR results determined from this Study to the design criteria designated by various

agencies worldwide.

(c) Comparison of the CBR results determined from this Study to the specification criteria of this Project for

purposes of analyzing the range and/or level of enhancement of the bearing and structural capacity

properties.

(d) Evaluation of heavy load performance in relation to the structural requirements.


As demonstrated in sub-section 4.4 of this Report, the consolidation test results is are predominantly applied

for the prediction of the post-construction secondary consolidation settlement.


6.8.1 Application of Principle Stresses within the Soil Elements

The principle stresses ’a and ’r are applied in carrying out the analysis of the deflection within the interface

of the overlaying and foundation layers in order to mainly determine the following facts.

(a) The magnitude and/or extent of the interface and layer deflection under dynamic loading.

(b) Analysis of the point load effect by the traffic tyre pressure of heavy trucks with respect to

each foundation pad.


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(c) Determine the level and extent of the vertical and radial stress distribution particularly

within the shear banding of the slip surface for developing effective countermeasures for

the stability of the foundation structure

(d) Determine shear stresses that would cause and resist failure.

6.8.2 Shearing Strength Test Results

Shearing strength test results were applied in;

(a) Determining the strength required to resist the forces and stresses that may act to cause

failure.

(b) Calculation of the stability of the foundation ground geo-structure

(c) Analysis of stability of the OPMC stabilized layers.

(d) Determination of bearing capacity factors for the design of the foundation structure on the

existing bearing ground.

(e) Analysis of the stability of bearing capacity of the foundation ground

6.9 Modulus of Deformation and Elastic Modulus Test Results

Application of the modulus of deformation E50 and elastic modulus Emax was made in reference to

(a) Deflection analysis as discussed in various preceding sections

(b) Prediction of the resulting quasi-elastic (initial) time dependent settlement caused by both

static and dynamic loading

(c) Prediction of cumulative settlement with increased repetitive loading over designated time

periods.

(d) Prediction of post-construction secondary consolidation settlement as comprehensively

discussed under various sections.


The application of results related to deformation properties and linear elastic range is discussed under sub-

section 4.6.3.

6.11 Durability Test Results

These results are utilized in analysis in order to:

Determine the suitability and extent of stabilization particularly for the sub-base and base course

materials.

Determine the resilience of the stabilized materials under particularly severe environmental and dynamic

loading conditions.


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CHAPTER 7

7. PAVEMENT STRUCTURAL DESIGN

7.1 Scope

This chapter determines the pavement design based on the US FAA/ ICAO method of Design, analyzes

various options and recommends the VE based design for the Isiolo Airport aimed at serving aircraft

with gross weights of up to 79,016kgs for B737-800 series.

The design is limited to the Airport Pavement and does not include geometric design or design for any

other of the airport facilities.

7.2 Fundamental Design Philosophy

The design largely adopts the recommendations made through the Advisory Circular (AC) No.

150/5320-6D dated April 30th, 2004, “Airport Pavement Design and Evaluation”.

Reference is also made to the 737 Airplane Characteristics – Airport Planning D6-58325-6 published in

May 1984 by Commercial Airplane Company, which is a Division of the Boeing Company.

The Design Philosophy is based on the United States Federal Aviation Administration (FAA) and the

International Civil Aviation Organization (ICAO) recommended practices.

The basic design considerations made herein include but are not limited to:

1. The flexible pavement design is based on CBR method of design.

2. Gear configurations are considered by adopting theoretical concepts and empirically developed

data.

3. Composite structural considerations have been made in reference to the surface course, base

course, sub-base and subgrade that can support a Boeing 737-800.

4. The design considers proper and adequate provision of hydraulic facilities as well as periodic

and preventive maintenance.

5. The design life considered is 20 years from date of completion of the pavement structure.

6. As cited in the Advisory Circular, the pavement structural thickness is determined on the basis

of theoretical analysis of load distribution through the pavement and soils, the analysis of

experimental pavement data, environmental factors, Case Study Analysis, among other

considerations (ref. to tables 7.2.1 – 7.2.3).

7. Reference is also made to Annex 14 to the Convention on International Civil Aviation Volume 1

in general and Section 2.6 of Chapter 2 regarding Strength of pavements, in Particular.


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Table 7.2.1 Summary of Major Design Considerations

Item Parameter Consideration

1. Aircraft Model and Specification - Wide Body aircraft – B737-800,

Ref. to Table 7.2.2

2. Airplane Configuration - 155,500lb (70,534kgs) to 174,200lb

(79,016kgs) Takeoff weight (TOW)

3. Landing and Takeoff Weights

3.1 Maximum Landing Weight

3.2 Maximum Takeoff Weight

-

-

66,381kgs

379,016kgs

4. Maximum Structural Payload - 21,319kgs

5. General Characteristics - Ref. to Table 7.2.3

6. General Dimensions including Ground Clearances Ref. to Fig. 7.2.1, Fig. 7.2.2

7. Landing Gear Type and Geometry (Footprint) - Double Dual Tandem Gear

Ref. to Fig. 7.2.3

8. Maximum Design Taxi Weight - 79,333kgs

9. Gear Tyre Pressures

9.1 Weight on Main Landing Gear

9.2 Nose Gear

9.3 Main Gear

-

-

-

75,855kgs

13.30kgf/cm2

14.41kgf/cm2

10. Maximum Pavement Loads - Ref. to Table 7.2.4

11. Landing Gear Loading on Pavement - Ref. to Fig. 7.2.4

12. Flexible Pavement Requirements adopting FAA Design

Method

Minimum Non-stabilized BC thickness = 150mm (P.49)

Minimum Thickness for Stabilized BC = 103mm (≈100mm)

Equivalency Factor of 1.45 is adopted (ref. Table 3-9 of

AC))

- Ref. to Fig. 7.2.5

Table 7.2.2 Technical Specifications for Boeing Aircraft detailing the B737-800

Measurement 737-800

Cockpit Crew Three

Typical seating capacity 162 (2-class)

189 (3-class)

Length (39.50 m)

Wingspan (34.32 m)

Tail height (12.5 m)

Weight empty 77,539 lb

(41,879 kg)

Maximum takeoff weight 146,300lb

(79,016kg)

Cruising speed

(at 35,000 ft altitude)

Mach 0.785

(519 mph, 834 km/h)

Maximum speed Mach 0.89 (594 mph, 955 km/h, 516 KN)

Required runway at

MTOW*

5,361 ft (1,634 m)

http://en.wikipedia.org/wiki/Seating_capacity

http://en.wikipedia.org/wiki/Pound_%28mass%29

http://en.wikipedia.org/wiki/Takeoff

http://en.wikipedia.org/wiki/Mach_number

http://en.wikipedia.org/wiki/Mph


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Maximum range

at MTOW

4,000nmi

Max. fuel capacity 21,018 U.S. gal

Engine models (x 4) CFMI CFM56-7

Engine thrust (per engine) 23,700lbf

Sources: 737 specifications, 737 airport report, 737-8 airport brochure

The 737 parasitic drag, CDP, is 0.022, and the wing area is 5,500 square feet (511 m2), so that f equals about

121 sq ft or 11.2 m². The parasitic drag is given by ½ f ρair v² in which f is the product of drag coefficient CDp and

the wing area.

Table 7.2.3 General characteristics of the Model 737-800 Aircraft

http://en.wikipedia.org/wiki/U.S._customary_units#Liquid_volume

http://en.wikipedia.org/wiki/Pound-force

http://en.wikipedia.org/wiki/Parasitic_drag


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Fig. 7.1 General Dimensions of the Model 737-800 Aircraft


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Fig. 7.2 Ground Clearances – Passenger Configurations Model 737-800 Aircraft

Fig. 7.3 Landing Gear Footprint for Model 737-800 Aircraft


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Table 7.2.4 Maximum Pavement Loads of the Model 737-800 Aircraft

Fig. 7.4 Landing Gear Loading on Pavement - Model 737-800 Aircraft


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Fig. 7.5: Pavement Thickness Design as per the Conventional Design.

Fig. 7.5 Flexible Pavement Requirements – U.S. Army Corps of Engineers Design Method S-77-1 and FAA

Design Method - Model 737-800 Aircraft

Determination of Thickness for This Study


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Fig. 7.6: Pavement Thickness Design using the OPMC GI-MC Technique;

7.3 Comparison of Design Data with Various Design Criteria

7.3.1 Comparison of Design Criteria for Physical, Strength and Bearing Capacity Parameters

In Chapter 5 comprehensive and detailed materials characterization and data analysis was carried out. In this

section, the data that was determined from the various tests and analysis is compared with the design criteria

specified by several International Agencies to establish its suitability as design parameters.

Table 7.3.1 presents a comparison of the results determined from The Isiolo Airport Design and design criteria

stipulated by various Agencies for critical design parameters such as Plasticity Index PI, Unconfined

Compression Strength (UCS) and California Bearing Ratio (CBR) for Pavements under Traffic Dynamic Loading.


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Table 7.3.1 Comparison of Design Criteria - Physical, Strength & Bearing Capacity of Stabilized Materials

Pavement Layer Source UCS

(MPa)

CBR

(%)

PI

(%)

Sub-base

Materials

TRL 0.75~1.5 > 70 < 10

AASHTO - - -

JRA 10 - < 10

KRDM >1.8 > 60 < 12

US FAA > 60 ≤6

This Study

(Existing Ground)

3.32 138 ≤6

Base Course

Material

TRL G: 1.5 ~ 3.0

H:3.0 ~ 6.0

> 100 < 6

AASHTO 2.8~5.25 - -

JRA 2.5~3.0 - < 9

KRDM 1.8 > 160 < 10

US FAA >80 <6

This Study (CGSG) 3.31 138 ≤6

Notes:

a. PI : Plasticity Index, UCS : Unconfined Compression Strength, CBR : California Bearing Ratio

b. TRL: Transport Research Laboratory, London, AASHTO: American Association of State Highway

Officials, JRA: Japan Road Association, KRDM: Kenya Road Design Manual.USFAA: United States

Federation of Aviation Administration.

c. Results from This Study were determined from tests performed on various OPMC Stabilized

Materials under 3 days cure Conditions

d. Cement additive percentage –Sub-base : 4~6%, Base Course : 4~8% :

This Study: 1 ~ 3% for Base Course.

e. CGSG : Cement-Geogrid Stabilized Gravel

In general, it can be appreciated that the granular fill (OPMC) material that was tested at Isiolo Airport yields

engineering design parameters that are well above the criteria stipulated by virtually all the Agencies

presented herein.

From the projections of the effects of curing [Chapter 5, Section 5.11], it can be inferred that the strength of

the stabilized Geomaterials increases with time. This can be confirmed from the laboratory test results where

the CBR after 7days cure is 213%.


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7.3.2 Comparison of Applicable Specification Criteria for Stabilized Natural Gravel and Design Parameters

The comparison of applicable specification criteria for stabilized natural gravel and design parameters

determined from this study is tabulated in Table 7.3.2.

Table 7.3.2 Comparisons of Spec. Criteria -Stabilized Natural Gravel & Design Parameters - This Study using

the OPMC Technique

Pavement Layer

Reference

PI

PM

CBR (%)

UCS

(MPa)

Subgrade Material Spec. _ <1200 _ _

This Study 62 492 50 1.20

Sub-base Materials Spec. <15 <240 > 30 1.5~3.0

This Study < 6 141~282 138 3.32

Base Course Material Spec. < 6 _ > 160 3.0~6.0

This Study < 6 - 138 3.32

It can be derived from Table 7.3.2 that the values determined from the research undertaken in this study

are superior in comparison to the Specification Criteria.

7.3.3 Comparison of Modulus of Deformation Parameters

One of the most important parameters for structural design of a pavement structure is the elastic

modulus. Table 7.3.3 presents a comparison of ranges of elastic modulus referred from various sources

and researchers as well as that determined from this study.

Table 7.3.3 Comparisons of Ranges of Elasticity Modulus for Structural Design from Various Sources

Pavement

Layer Type

(Material)

Elastic Modulus Values, Emax (MPa)

This study Fossbereg

St: 6~8%

Wang

/Mitchell

St : 3~6%

Helekelom

/Klomp

St : 3~8%

Mitchell/

Shen

St : 7%

Before

Improvem

ent

After

Improvemen

t

Subgrade 8 355 _ 140 ~ 1200 _ _

Sub-base (St ; 3%)

2561

_ _ 350~ 21 00 1400~

6300

Base

Course

2768 7000 ~

15000

_ 10500~

18900

Lean

Concrete

m

2

_ _ 15000~

30000

_

PCC _ 21000~

35000

_ _

_

Notes:

1. St : Percentage of Cement Stabilization excluding the PCC and Lean Concrete

2. Results from This Study were determined from tests performed on Cement-Geogrids Stabilized OPMC

Materials tested subsequent to 7 days cure + 7 days Soak Conditions


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3. Cement additive percentage –Sub-base: 3%, Base Course: 3% for this Study.

4. From table 5.11.1, the strength of the base layer will increase with time hence after several days of

curing, the base layer would be adequate.

As can be noted from Table 7.3.3 the comparison is made of pavement materials basically stabilized with

cement at percentage ranges of 4~8%. However, it is important to recall that the base course material in this

study is natural gravel material treated with only 2% cement.

It can be distinctly derived that the elastic modulus results from this study exhibit higher values than those

reported by other Researchers or Agencies in spite of the lower percentage of cement.

7.3.4 Conclusions Regarding Design Parameters

From the comprehensive and detailed analysis undertaken in Chapter 5 followed by the analysis done in the

foregoing sections, it can be concluded that the Cement-Geogrid Treated Geomaterials analyzed in this Study

exhibit high safety factors and can certainly be adopted for the design and construction of the sub-base/base

course layers of the Airport Pavement.

7.3.5 Adopted Design Criteria

The following standards and/or design criteria are hence mainly adapted in appropriation to the suitability,

relevance and cost-effectiveness for the purposes of the design of the Isiolo Airport Pavement Structure.

1. U.S. FAA : United States Federal Aviation Administration

2. ICAO: International Civil Aviation Organization

7.4 Evaluation of Air Traffic Volume and Growth

Evaluation for traffic volume and growth was undertaken based on the US FAA Method.

Considering an annual growth rate of approx. 4% over the design life of 20 years, Equivalent Annual

Departures of 3,000 were adopted.

7.5 Engineering Analysis of Geomaterial Properties

Comprehensive engineering analysis of the properties and characteristics of the existing soils and improved

and/or selected Geomaterials was undertaken in Chapter 5 of this Report.

7.6 Evaluation of Strength of Existing Subgrade

7.6.1 Relatively Stable Geomaterials

Average subgrade CBR values were determined per location and the mean and section Design CBR values

computed from the results presented in Chapter 5 of this Report.

The existing pavement structure exhibit high CBR values, an average in situ CBR of 62% compared to the

surrounding subgrade which is predominantly Black cotton soil.


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7.6.2 Analysis of Problematic and/or Expansive Soils

The subgrade soil is predominantly black cotton soil whose analysis of material properties has been

comprehensively analyzed in Chapter 5.

7.7 Determination of Pavement Structural Design

7.7.1 Determination of Total Pavement Thickness Required

Subsequent to determining the Mean-section Design CBR values for the subgrade and the sub-base (ref. to

table 7.7.1), the weight on the main landing gear was determined from Fig. 7.2.4. Having pre-determined the

design aircraft and the number of annual departures of the design aircraft, the design curves in Fig. 7.2.5

based on the U.S. Army Corps of Engineers Design Method S-77-1 and the U.S. FAA Design method, the total

pavement thickness required were derived.

The existing subgrade soil strength values indicate very low CBR and UCS strengths under soak conditions. The

Kenya Road Design Manual suggests that such soils need to be excavated and replaced with good quality

granular fill. In the same stroke, a conventional CBR strength of 10% was taken to represents the improved

subgrade strength where the construction had been undertaken conventionally as suggested by the same

manual.

In this Design Ground Improvement-Moisture Control Techniques were used to improve the in-situ strengths

of the subgrade. The CBR mean value of the subgrade is 62%; but a value of 50% has been used. There is

inclusion of the geofabrics which mobilizes the stresses within the Black Cotton soil subgrade which in turn

enhances the overall strength of the subgrade material.

Table 7.7.1 is a summary of the main design parameters that were adopted in determining the total pavement

design thickness.

Table 7.7.1 Summary of Main Design Parameters Adopted for conventional design

Design

Aircraft

Maximum

Design

Taxi

Weight

(Kegs)

Weight on

Main

Landing

Gear (Kgs)

Number of

Equivalent

Annual

Departures

Design CBR (%) Design

Life (yrs)

Remarks

Improved

Subgrade[after

replacement]

Sub-base

B737-800 79,333 75,855 3000 10 88 20

7.7.1. a Conventional Design:

Based on the data presented in Table 7.7.1, the Total Pavement Thickness required was determined from Fig.

7.5. As stated in 7.7.1, “The existing subgrade soil strength values indicate very low CBR and UCS strengths

under soak conditions. The Kenya Road Design Manual suggests that such soils need to be excavated and

replaced with good quality granular fill. In the same stroke, a conventional CBR strength of 10% was taken to

represents the improved subgrade strength where the construction had been undertaken conventionally as

suggested by the same manual.” The CBR value for the conventional approach is a maximum of 10%. From Fig.

7.5, the pavement thickness is determined. The summary and conclusion on CBR is analyzed in Chapter 5

section 3.

Therefore, the Total Pavement Thickness required is ≈16 inches or 400mm.


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Conventionally, the design considers a Total Pavement Thickness of 400mm assuming that the subgrade is

competent i.e. after improving it to CBR 10%. Note that the usual conventional provision when constructing on

Black cotton soil is to excavate it and replace with qualified material.

7.7.1 b OPMC – MC Ground Improvement Technique

With Ground Improvement-Moisture Control Technique, use of 200mm and 400mm thick sand column piles

are used for Ground Improvement and Moisture Control of the Black Cotton Soil Subgrade. From chapter 5,

we have seen that the in situ strengths of the subgrade are higher when the subgrade is Unsoaked/dry and

drops tremendously when soaked/wet. The GI-MC technique is meant to control moisture levels in the

subgrade. It also incorporates geotextile/geofabrics which will enhance the mobilization of the stresses within

the Black Cotton Soil subgrade thereby improving further the strength of the subgrade. The geofabrics will also

act as a filtration/separation membrane and will act to stop the ingress of fines into the well graded base/sub-

base granular material.

A CBR value calculated/determined from chapter 5 of 50% is used from Fig 7.6, the Total Pavement Thickness

required is 200mm. (Ref. to fig 7.7 of this report)

7.7.2 Thickness of Sub-base

The bearing capacity, strength and deformation resistance of the existing pavement and subgrade were

technically evaluated and results presented in Chapter 5.

Due to the coupled effects of cementation and Long Term Consolidation (LTC), the section with existing

pavement exhibits high bearing capacity and strength values (ref. to Section 5.3 of Chapter 5 of this Report).

However the rest of the section falling on BCS subgrade exhibit low bearing capacity and strength values

Consequently, 200mm is considered to be the adequate combined thickness of the Base Course and a further

75mm is applied for the Surface Course

7.7.3 Thickness of Surface Course

The thickness of the surface course was pre-determined as 75mm (40mm Wearing Course + 35mm Binder

Course) and was technically evaluated and found to be adequate (ref. to Subsection 7.8.1 and 7.8.2 of this

Report). Note that in the case of the Apron the Wearing Course is Concrete Paving Blocks, 80mm thick with

crushing strengths of 49MPa.

7.7.4 Thickness of Base Course

The base and sub-base courses are combined in this design and there total thickness is 200mm. Tensar TX

170G geogrids are used to mechanically stabilize the base layer thereby enhancing the durability, longevity

and versatility of the pavement. Through the confinement of the granular material, the geogrid will maintain

and improve the mechanical stability of the pavement once the pavement structure starts showing signs of

deterioration due to age and increased passes of traffic.

7.7.5 Thickness of Non-Critical Areas

The thicknesses of the non-critical areas [shoulders] are indicated in Fig. 7.8 and Fig. 7.10 for Section A and B

respectively.


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Plan View of Isiolo Airport

Fig 7.6 Plan of the Airport showing the TWO pavement types with other details


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Fig 7.7 Plan View and MC Sand Column Details for BCS Subgrade Improvement


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7.7.6 Typical Cross-section A

The Typical Cross-section of the Isiolo Airport pavement structure designed in accordance with the U.S.

Federal Aviation Administration (FAA) and the International Civil Aviation Organization (ICAO) Design Codes

and stipulations is shown in Fig. 7.7.1.

Fig. 7.8 Typical Cross-section A


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Fig. 7.9: Plan View and MC Sand Columns Details For Section A


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Typical Cross Section B

Fig. 7.10: Typical Cross-section B


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Fig. 7.11 Plan View and MC Sand Column Details for Cross Section B


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7.8 Analysis of the pavement Design

Under this section, each pavement layer in the structure is analyzed to determine their adequacy and

performance under the design conditions and loadings. The main factors employed in undertaking this analysis

are Structural Capacity Analysis and Deformation Resistance Analysis.

7.8.1 Analysis of Structural Capacity

The Method was adopted in computing and analyzing the structural capacity of the composite pavement

structure. The value of is calculated from the following equation.

(7.1)

Where,

= Conversion Coefficient presented in Table 7.8.1.

= Thickness of each pavement layer in cm.

For a cost effective design for the Isiolo Airport, the Target including a global Safety Factor of 1.25 was

determined to be .

This caters for a projected Air Traffic for the B737-800 design aircraft and 3,000 Equivalent Annual Departures

for a Design Life of 20 Years.


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Table 7.8.1 Conversion Co-efficient for the Calculation of

Pavement

Course

Method and

Material of

Construction

Conditions Standard

Coefficient, an

OPMC/GG

Coefficient, an(OPMC)

Surface &

Binder

course

Hot asphalt mix for

surface and binder

course

1.00 Glasstex

Reinforced

= 1.35

Base Bituminous

Stabilization

Hot-mixed stability:

350kgf or more

Cold mixed stability

250 Kgf or more

0.80

0.55

OPMC Level

10 = 0.94

8 = 0.86

Cement

Stabilization

Unconfined compression

strength (7days):

30 Kgf/cm2

0.55 OPMC Level 6 =

0.78

Lime stabilization Unconfined compression

strength (10 days):

10kgf/cm2

0.45 OPMC Level 4 =

0.65: Cement/Lime

Combination

Crushed stone for

mechanical

stabilization

Modified CBR value: 80 or

more

0.35 OPMC Level 2 =

0.58

Slag for mechanical

stabilization

Modified CBR value:

80 or more

0.55 OPMC Level 6 =

0.78

Hydraulic slag Unconfined compression

strength (14 days) 12

Kgf/cm2 or more

0.55 OPMC Level 6 =

0.78

Sub-base Crusher-Run, slag,

sand, etc

Modified CBR value:

30 or more

20 to 30

0.25

0.20

OPMC Level 2 =

0.58

OPMC Level 3 =

0.62

Cement stabilization

Unconfined compression

strength (7 days):

10kgf/cm2

0.25 OPMC Level 4 =

0.65: Cement/Lime

Combination

Subgrade Black Cotton Soil 0.05

(Source: AASHTO, AAI, ASTM, Japan Road Association 1989 and XXIIRD PIARC World Road Congress, Paris

2007)

Notes: Conversion coefficients listed in Table 7.8.1 indicate the ratio of the thickness of the pavement by each

method and material of construction to the thickness of hot asphalt mix for the binder and the surface courses

corresponding to the thickness of each material. Thus, the term nnTa of Equation in 7.1 indicates the

corresponding thickness of the n-th layer converted thickness of hot asphalt mix for the binder and surface


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courses. For example; 1 cm of pavement adopting mechanical stabilization corresponds to 0.35 of pavement

adopting the hot asphalt mix method, and a 20cm of pavement using the hot asphalt mix method would

therefore be (0.35×20=7).

Also note the OPMC conversion Values determined empirically for varying OPMC Stabilization levels published

in the XXIIRD PIARC World Road Congress, Paris 2007.

Structural Capacity of Proposed Design, Cross-section B

In this case the , is computed as:

= 1x7 +0.62 x 20 + 0.35 x 40 + 0.05 x 33

= 35 > 25 [OK]

Structural capacity of proposed pavement, Cross section A

In this case the is computed as:

= 1x7 +0.62 x 20 + 0.35 x 40 + 0.05 x 33

= 35 > 25 [OK]

Deformation Resistance of the Pavement Section

The schematic cross-section of the varying layers of the pavement structural configuration of the Design is

shown in Fig. 7.8.8-1 and 7.8.8-1 below.

=4,419MPa

=4,419MPa

=4488MPa

=2,179MPa

=492MPa

Fig. 7.13 Schematic Cross-section of varying Layers of Proposed Design, Cross section A


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Fig. 7.14 Schematic Cross-section of varying Layers of Proposed Design, Cross section B

=4,419MPa

=4,419MPa

=4488MPa

=2,179MPa

=65MPa


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Table 7.8.1 Summary of the structural capacity, deformation resistance of the composite pavement

Cross-section A

Cross-section B

TA TA qu,A[Mpa] qu,B[Mpa]

T1 Asphalt concrete ACWearing/Binding

Course 1 7 7 4.50 4.50 4,419.00 4,419.00

T2 OPMC Level 3

Subbase

Geomaterial + Geogrid 0.62 20 20 3.32 3.32 5,331.15 5,331.15

T3BCS

Ground Improvement

Subgrade 0.35 20 40 1.38 1.38 2,179.02 2,179.02

where:

ERCA- resultant ER for cross section A

ERCB- resultant ER for cross section B

492.32

1414

1317100

1.46

65.13

Composite pavement

ERCB

T1+T2+T3+

T40.94

0.05

Composite pavement

ERCA 100

0.83 T4Existing Black

Cotton SoilSubgrade 0.05 53 33

S/No Description Pavement LayerOPMC/GG

CoefficientE

Bmax[Mpa]

qu[Mpa]E

Amax[Mpa]

The Table above shows the results of the individual layers and the composite pavements after one day cure.

The strength as explained and inferred in Chapter 5 will increase with time.

The summaries from table 7.8.1 above shows that our proposed pavement structure is adequate to perform as

a runway that will handle Boeing 737-800 aircraft with annual departures of 3000 flights for 20 years.

Conclusion:

The design used in this project realizes a reduction of the overall thickness of about 125mm as compared to

the conventional designs.


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CHAPTER 8

8. ANALYSIS OF TIME DEPENDENT STRUCTURAL SOUNDNESS

The Analysis of Time Dependent Structural Soundness is still under investigation. We therefore present the

Model that we used in the Design of Songwe airport in Tanzania. This can be used as a case study.

8.1 Analysis of Structural Capacity Deterioration with Time Progression based on the SCDR Model

8.1.1 Definition of Structural Failures

Distinctively, there are two different types of pavement failure. The Structural Failure includes a collapse of

the pavement structure or a breakdown of one or more of the pavement components of such magnitude to

make the pavement incapable of sustaining the loads imposed upon its surface and through the pavement

structure. The second type is classified as Functional Failure and may or may not be accompanied by structural

failure but is such that the pavement will not carry out its intended function without causing discomfort to

passengers or without causing high stresses in the vehicle that passes over it due to roughness. Obviously the

degree of distress for both categories is gradational, and the severity of distress of any pavement is largely a

matter of opinion of the person observing the distress. As an example, consider a rigid pavement that has

been resurfaced with an asphaltic overlay. The surface may develop rough spots as a result of breakup in the

bituminous overlay (functional failure) without structural breakdown of the overall structure. On the other

hand, the same pavement may crack and break up as a result of overload (structural failure). Maintenance

measures for the first situation may consist of resurfacing to restore smooth – riding qualities to the pavement.

However, the structural type of failure may require complete rebuilding/reconstruction.

8.1.2 Fundamental Theories/Concepts Applied in Developing SCDR Model

(1) Theories and/or Concepts Considered

The choice of an effective analytical method depends predominantly on the choice of the backbone

engineering theories, principles and concepts and the extent to which they translate to pragmatic application.

For these purposes, the theories and concepts applied are based on fundamental theories, principles and

concepts introduced in Chapter 4.

The generalized equation of the existing road conditions can be expressed as a function of loading conditions,

pavement type (structurally), pavement layer quality, structural thickness as well as intrinsic material

properties depicted in Equation 8.1. v

msecidfc tePPtfR ,,,,, (8.1)

Where,

cR = road condition, df = dynamic load factor, it = response mode factor of layer of the pavement

structure, cP = pavement configuration, eP = pavement layer quality, et = structural thickness, v

ms =

parameter delineating moisture – suction variation.

On the other hand, the extent of distress of deformation can be derived based on the theories introduced in

the preceding sections applied for carrying out back analysis of the deformation history of a distressed

pavement structure. In a generalized state, this can be expressed as shown in Equation 8.2.

o

ijyi

oc

f

oc

f

oc

fdh fqpf ,,',,',',' (8.2)


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where,

dh = parameter delineating deformation history ' = consolidation stress ratio, ' = modifier

between Isotropic and Anisotropic stress paths, oc

f

oc

f qp ,' = invariant stress under over consolidation

conditions, ,

f = Angle of Internal Friction within the failure zone.

The following theories, concepts and equations are then employed as the inputs for the generalized state

model.

Dynamic Loading Effects

Although the equivalency law and hence the fourth power law equations developed at the AASHO

road test incorporate actual dynamic load effects based on measurements of the overall loss of

serviceability that included dynamic components, attempts to modify these equations have constantly

been made. In this case, the equation proposed by Eisenmann (1975) containing a quantifier , known

as pavement structure stress factor, is applied. This equation is adopted because it is considered to be

the best mathematical representation of the theory of serial basins. In this relation, it is assumed that

dynamic wheel forces are Gaussian, i.e. normal distributions. The value deduced of the fourth power

of instantaneous wheel force is given by:

4

tpE =442 361 StVV PCC (8.3)

where, P (t) = instantaneous tyre force at time t, Pst = E [p (t)] = static (average) tyre force, Cv =

coefficient of varieties of dynamic tyre force and E [ ] = expectation operator. Eisenmann (1978)

further modified Eq. (8.3) to account for the effects of wheel configuration and tyre pressure in the

form of Eq. (8.4)

4

.stIII P (8.4)

where, = 1+62

VC +34

VC (dynamic oil drilling pad factor), I = parameter accounting for wheel

configuration for either single or dual tyres and II = parameter accounting for tyre contact pressures.

Intuitively, and ’ are dynamic versions related to the AASHO load equivalent factor (LEF) in the

forms:

K = vLEF (8.5)

and,

k4

IIIV LEF, k = ( .stP )-4

Transversal Propagation of Stress Induced Waves

The concept of serial deflection basins is introduced by considering the dynamic wheel load concept.

It is assumed that the deflection basins formulated can be mathematically represented by the


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damping effects of the pavement layers either in a composite or independent form. The damped

oscillatory equation of motion is therefore adopted.

o

ht

ord thec5.02

0

2sin (8.6)

where, rd = rebound deflection, Co= constant representing the initial conditions of loading,

d=damping factor of the pad foundation structure related to layer stiffness, t = response time

measured, = angular frequency and = constant representing the initial position and condition of

deflection measurement.

The concept of energy was also applied in analyzing the curvature of the deflection basin in relation to

the elastic moduli energy equation, expressed as follows.

0

5.022

0

2

0

5.022

0

222

0

22

0 sin5.0)( thwfthwCoshweCtE ra

ht (8.7)

where, fr is the force constant and la=axle load. It is further considered that the energy decreased

exponentially with the increase in time and is expressed as:

22 2/12/1)(

rrda fdt

d

dt

tdE (8.8)

Theory Of Applying Excitation Truck And Vibration Roller

The excitation truck and vibration roller were used for purposes of studying the impact and

magnitude of disturbance on the quantities of the deflections measured, longitudinal deformation,

transversal rebound characteristics and total pavement structural response. Effects of the variation of

the speed of the excitation and vibration modes of the vibration roller are quantitatively analyzed

from the following relation of steady state motion, completely specified by an amplitude b and phase

angle .

For low driving frequencies, the phase angle is expressed as:

02

arctan22

0

h (8.9)

In this case the driving force and resulting deflection are in phase hence the amplitude is expressed

as:

5.02222

0

0

4hw

fb (8.10)

For high driving frequencies the amplitude is considered to be


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5.0224

0

4h

fb (8.11)

In cases whereby d is small for light damping then:

2

0fb (8.12)

The phase angle is then given by

22

0

2arctan

hw (8.13)

In such a case as the frequency of of the impressed force is increased, the amplitude decreases

and the phase angle tends towards

Shear Wave Propagation Through Pad Foundation Layers

The analysis of the shear wave propagation through pavement structural layers is carried out by applying the

concepts related to the linear (LIN) and equivalent linear (EQL) methods. These methods of analysis are

commonly made by multiple reflection of vertically propagating horizontal components of shear waves though

multiple layered profile one dimensional system Assuming the deflection at any layer n is given by

iwt

rdrdrd eZtZ1 (8.14)

where, rd is the total displacement .The equation of motion is then given by:

tZZG

t

n

n

n

n

n

rd

n 2

3

2

2

2

2

(8.15)

where, ,2 nnn hG density of pad foundation layer, G = shear modulus and h is damping.

The solution of the resulting differential equation for the steady state harmonic motion is obtained as follows:

Zik

n

Zik

n

n

rdnn eFe (8.16)

and,

Zik

m

Zik

nnnnnn eFeEGik (8.17)

where, by

n

n

nG

pk (8.18)


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Where, m = shear stress at layer n, KN = wave number layer n and En and Fn are amplitudes of the upwards

and downwards bound waves.

Applying the conditions of continuity at the interface of the layers and the condition that shear stress at the

surface is zero, yielding E1=F1, then the transfer function between any layer can be quantified as:

nn

nn

nmfe

feA (8.19)

where, Anm = transfer function between layers n and m, ne =1E

En and 1F

Ff m

n . These facilities the

analysis of the unknown motion in other layers provided that the transfer function and input motion at the

layers are known.

Consequently the acceleration and the strain can be computed from the deflection functions expressed as:

twZKi

n

tKi

nn

rdn

rdn

n

eF

e

ttZ 2

2

2

1 (8.20)

and ,

twZKi

n

tKi

n

n

n

rdn

n

n

eF

eik

2

(8.21)

where, n

rd = acceleration in layers n and n =strain in layer n. Detailed description of the theoretical

background and analytical procedure are discussed by Kanai (1951) Haskeu (1953) Schnabel (1971) and Kanai

(1983).

Correlation of Response Time to Elastic Properties.

Wave propagation techniques are usually used to determine the elastic modulus of in-situ Geomaterials. In

applying this method a common assumption is that the material behaves as a linear elastic material under

isotropic conditions. Based upon such theoretical consideration, the models of the material can be determined

from the following equation.

gn

s

212 (8.21)

where, E= Elastic modulus = Poisson’s ratio (values of 0.4 for asphalt concrete and 0.45 for aggregate base

and subgrade) proposed by the Asphalt Institute were adopted in these analysis, Vs= shear wave velocity n =

density of layer n and g = acceleration of gravity.

In this study, it was assumed that since Vs= Lf where, L= the wavelength and f=frequency them Vs tr

(response time). Measured values of t were then used in computing the layer depth to determine the

responsive layer and estimate the corresponding elastic modulus.


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Back Analysis of Distressed Pad Foundation Deformation History.

The Constitutive model on cyclic plasticity for Geomaterials based on non-linear kinematic hardening theory

proposed by Yashima et al. (1994) is adopted in attempting to back analyze the deformation history of the pad

foundation structure. This model was chosen because of its incorporation of the non-linear kinematics

hardening rule. When incorporated into an overstress type of model, it is found to be effective in expressing

the changes in retardation in the strain rate direction upon a corresponding change in the direction of the

stress. Furthermore this model is found to reproduce to an appreciable extent, the plastic damage during

cyclic or repeated loading. By taking into account the effects of sub grade layer material into the sub base, the

constitutive model for clay is adopted in simulating the composite yield characteristics of these layers, while

the distress behavior of the upper pad foundation consisting of the unbound crushed aggregate base course

and the asphalt concrete, are analyzed by modifying the theories in the constitutive model for soft rock.

Constitutive model applied for lower pad foundation layers

The viscoplastic model for over consolidated clay extended to a cyclic model by Oka (1988) is applied. The

static yield functions that account for changes in the stress ratio are given as follows:

012

1****

1 Dijijijijy Rxxf (8.22)

where, 1DR = parameter defining the elastic region and *

ijx =the kinematics hardening tensor. By introducing

the non linearity of the kinematics hardening, *

ijx can be written as

vp

ij

vp

ijij dxdeABdx *

1

*

1

* (8.23)

In which *

1A and *

1B are the material constants and *

ijde is the increment of the viscoplastic deviatoric strain.

The second invariant of the increment of the plastic deviatoric strain is derived as:

21

vp

ij

vp

ij

vp deded (8.24)

For the first yield function, the plastic potential is assumed to be:

0')1(

'1*~21

****1 mamnMijxijijxijg (8.25a)

where, '

)1(ma = material parameter and *~M is the stress ratio when the layers are under maximum

compression condition: Considering the over consolidated boundary surface between the NC and OC zones to

be expressed as:

01~ '

)1(

'**

0 mamnmb Mf (8.25b)


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In the NC Zone 0bf , *~M is kept constant i.e., *~

M =*~mM whereas in the OC region, it is defined as:

0bf , *~M is defined as:

''*~mcmnM (8.26)

where, the current stress ratio 21

***

ijij and ''

mbmc exp (**

0 / mM )

Estimation of Consolidation and Shear Stress Paths

The input parameters for the constitutive model introduced in the preceding section were derived from the

following theories and concepts. As the repeated loading progresses, the cumulative effects are back analyzed

by applying the concepts of consolidation and shear stress ratio functions under normally consolidated (NC)

conditions introduced by Mukabi and Tatsuoka (1996) and Mukabi (2001d). In so doing, the initial stresses are

computed from the experimental results of full scale trial sections (Mukabi, 2002; Gono et al., 2003, this

conference) .The cumulative stresses are then derived by considering the average loading rate and cumulative

repeated loading over a given period of time. Once the maximum deviator and mean effective stresses are

determined, the stress ratio functions, defined from the following expressions proposed by Mukabi and

Tatsuoka (1999b) and Mukabi (2001d) are applied.

BA CSR (8.27)

Where, A and B are material properties, and the consolidation stress ratio function CSR , which is

independent of the effects of loading rate, is derived from the relation max

1

~ qCSR

, whereby '= function

of normalized angle of internal friction expressed as I

Q

A /' (A: An isotropic I: Isotropic) and maxq =

maximum deviator stress. ' can be determined from the quasi-empirical equation (Mukabi, 2001d) expressed

in general form as:

SRSRSR /' (8.28)

Where, ASR and BSR are stress ratio constants and 'pqSR is the invariant stress ratio variable.

The antistrophic stress path is derived from the isotropic one by introducing a modifier proposed by Mukabi

and Tatsuoka (1999b) expressed as:

CSRK CSRI

I

.

max (8.29)

where, max = (q/p’) at qmax, KI=1 and CSR= consolidations stress ratio. The modifier is applied in the relation

pq .

On the other hand, the invariant stresses and angle of internal friction under over consolidated (OC) condition

were derived from the flowing correlations proposed by Mukabi (2001d).


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NCoc

o

NC

o

NCNC

ooc

CSRAKK

qKq

..

. maxmax

(8.30)

where,OC

OxK'sin fOCRK OC

Ox

and

f

OC

OxK 'sin1

The corresponding mean effective stress, OC

fp 'and angle of internal friction

OC

f

' are given by:

NC

C

NC

f

OC

C

NCOC

O

NC

O

NC

OOC

fp

PP

CSRAKK

Kq

'

''

'

. (8.31)

and ,

NC

fNCOC

O

NC

O

NC

OOC

fCSRAKK

K '1

'

. (8.32)

Constitutive Model Applied for Upper Pad Foundation Layers

Adachi and Oka (1992) proposed that the stress history tensor is a function of the effective stress history with

respect of the strain measure. This history tensor, *'O

ij is given by

( ''/'exp1 '

0

*' dZZZZT

ij

ZO

ij (8.33)

where, dz= Zdede ijij ,21

= strain measure, T=material parameter which controls the strain-hardening and

strain-softening phenomena and deij is the increment of deviator strain tensor.

The plastic potential is assumed to be:

01~

'

'

*21

****

1b

bMxxg

mb

m

nijijijij (8.34)

The OC boundary is given as :

01~

'

'**

0b

bMf

mb

mnmb

(8.35)

The OC region is therefore defined as:

b

bM

mb

mn '

'*~

(8.36)


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Fig 8.1 Depiction of Determining Period and Level of Maintenance Based on the SCDR Model

8.1.3 Analysis of Structural Capacity

1) Initial Structural Capacity

It is imperative, when undertaking the design of flexible-pavement structures, to consider factors such as

subgrade characteristics, pavement layer strength and conditions, load and traffic parameters, environmental

conditions as well as the economics of design and construction.

Some of the major factors that affect the status or condition of a pavement structure include the Relative

Damaging Effect (RDeff.), which is related to the ESAL, variation in quality of materials prompted by

environmental factors, deterioration in pavement layer thickness through loss of aggregates and infiltration of

inferior lower quality materials into the upper layers of the pavement structure.

The concept of remaining life can be transposed or defined in terms of the existing structural capacity by

application of the following equation.

rfeffSCRL

e

SC xRDfff .

Re (8.37)

WhereRe

SCf represents the existing structural capacity, RLf = Remaining Life Factor, Re

SCf = Structural Capacity

Factor of a newly constructed or reconstructed pavement structure in which case Re

SCf =1 and .effRD = 0.298 is

the damaging factor while rf = defines contribution of a multitude of factors affecting the magnitude of the

damaging effect defined as:

PSIRSFPSFrf xx

where △PSF= Present Serviceability Factor, △RSF = Redundant Serviceability Factor and △PSI = Present

Serviceability Index computed as △PSI=3.34 for this Project Road and △PSF = 0.18, whereas △RSF is derived from

the expression


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SB

C

SB

f

BC

C

BC

f

AC

C

AC

fRSF FxCFxCFC01.01 (8.38)

SB

f

BC

f

AC

f CandCC , are conversion factors for Asphalt Concrete, Base Course and Sub-base respectively,

while SB

C

BC

C

AC

C FandFF , are correction factors related to the deterioration of pavement layer thickness. In

the case of a newly or reconstructed pavement structure, it is assumed the SB

C

BC

C

AC

C FandFF , = 1. However,

based on the SCDR Model, the time dependent deterioration structural factor can only be computed where Nt

> 2.2 years.

Considering structural and stability safety factors as well as quality control deficiencies during construction,

the initial structural capacity factor defined at Nt=2.2 years is computed as below for design parameters

determined as per standard specifications.

△ rf = 0.18x1.019x3.34

= 0.613

Hence,

2.2(

)(tNe

stSCf =1-0.613

2.2(

)(tNe

stSCf =0.824

While, for Geomaterials exhibiting enhanced engineering properties, △RSF = 0 hence △rf = 0, consequently,

2.2(

)(tNe

enSCf =1

2) Deterioration of Structural Capacity with Time Progression

Some of the major factors that contribute to the deficiency with time, of the structural capacity and

serviceability level of an existing pavement structure were mentioned in the preceding Sub-Section 8.1.2. This

deterioration with time is known to grossly affect the performance of pavement structures.

The deterioration with time of the structural capacity factor t

SCf after Nt = 2.2 years can be defined by Eq.

(8.39) below,

15.1log t

e

SC

t

SC Nxff (8.39)

Based on the foregoing concepts and equations, the following equation is applied for soft clayey soils.

SCtSCtSCSCt CNBNAf (8.40)

Where,

SCtf Time dependent Structural Capacity Factor

SCA 0.001, SCB 0.0507 and SCC 1.13 are Structural Capacity-Time related constants


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tN Time Progression in Years

On the hand, for OPMC, mechanically and/or chemically (treated) stabilized Geomaterials, stiff soils and

relatively hard rock, the following equation is applied.

(8.41)

3) Analysis of Influence of Environmental Factors

Environmental factors such as moisture-suction variation due to seasonal cycles, inferior material intrusion as

a result of the combined effects of dynamic loading and water infiltration (pumping) and land use affecting the

structural pavement layer thickness are known to affect the structural capacity and serviceability levels of a

pavement structure.

In order to determine in a quantitative manner, the magnitude of the influence of these factors in relation to

the depreciation (deterioration) of the structural capacity of a pavement structure, the following equations are

adopted.

The environmental factors time dependant generalized equation is factored as and expressed as,

(8.42)

The environmental factors time dependant depreciating variation factor, is defined as,

(8.43)

Where,

= Moisture-Suction Depreciating Factor

= Inferior Material Intrusion Depreciating Factor

= Pavement Layer Thickness Depreciating Factor

The time dependant Structural Capacity depreciating factor is therefore computed as,

(8.44)

= Structural Capacity Depreciation Factor

= Initial Structural Capacity (pre-consolidation)

= Time Progression in Years

= 2.2years (Reference Time Period)

= 0.824 (Reference Structural Capacity Factor)


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8.2 Analysis of Time Dependent Structural Capacity for Varying Designs of Isiolo Airport

In this Study, five (5) pavement designs have been considered. These designs are presented in Chapter 7 of

this Report.

In order to arrive at the most optimum VE based conclusion and recommendation, it is considered vital to

incorporate the element of maintenance period and costs accordingly.

The appropriate periods and modes of maintenance are determined in terms of a direct proportional

relationship between maintenance needs and costs to the deterioration of the pavement structural capacity

with time progression.

Table 8.2.1 is a summary of the main parameters that are adopted in carrying out these analyses for the

various designs considered

Table 8.2.1 Summary of Main Parameters Adopted for Analysis for Varying Designs

Option Type Layer

Type

Main Analysis Parameters

CBR (%) qu

(MPa)

Emax (a)ELS x

10-3

(%)

EXISTING

Design

Composite 161 3.90 3,233 0.8313 32.25 0.72 1 1 1

USFAA/ICAO

Based

Composite 195 4.71 4,477 1.0045 30.8 0.87 1 1 1

PROPOSED

OPTION

Composite 224 5.42 5,141 1.1546 46.4 1.00 1 1 1

Notes:

CBR : California Bearing Ratio applied for Composite Base Course, Sub-base and Subgrade only

: Unconfined Compressive Strength

: Elastic (Young’s) Modulus

: Elastic Limit Strain

: Structural Pavement Thickness Indicator

: Initial Structural Capacity Ratio

: Moisture-Suction Depreciating Factor

: Inferior Material Intrusion Depreciating Factor

: Pavement Layer Thickness Depreciating Factor

All parameters are considered the initial parameters that are determined during the Virgin Loading

stage.

In undertaking these analyses, the effects of consolidation in enhancing the bearing capacity, strength and

deformation resistance during the first period of dynamic and static loading have not been taken into

consideration.

Tables 8.2.2 to 8.2.8 are a summary of the deterioration factors and depletion of the structural capacity for the

varying designs, while Figs. 8.2.1 to 8.2.7 are a graphical depiction of the corresponding trend of the structural

capacity with the progression of time.


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In this case, the computations postulate scenarios of “WITH MAINTENANCE” scenario where only consistent

routine and periodic maintenance are undertaken without full scale Recarpeting (resurfacing) and “WITHOUT

MAINTENANCE” scenario whereby full scale Recarpeting (resurfacing) would then become necessary at prior

to the expiry of the Design Life.

Table 8.2.2 Structural Depreciation Factor for EXISTING Pavement.

0

5

10

15

20

25

30

35

0 2 4 6 8 10 12 14 16 18 20 22

Re

sult

ing

T A

Time Progression, Nt (years)

Resulting TA With Maintenance Vs. Time

0

5

10

15

20

25

30

35

0 2 4 6 8 10 12 14 16 18 20 22

Re

sult

ing

T A


Resulting TA WithOUT Maintenance Vs. Time

Fig 8.2 Graphical Depiction of Depreciated Structural Capacity Factor and Resulting “WITH Maintenance”

Scenario as well as “WithOUT Maintenance” effect


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Table 8.2.3 Structural Depreciation Factor for U.S. FAA – ICAO Based Design option.

0

5

10

15

20

25

30

35

0 2 4 6 8 10 12 14 16 18 20 22

Re

sult

ing

TA



0

5

10

15

20

25

30

35

0 2 4 6 8 10 12 14 16 18 20 22

Re

sult

ing

TA



Fig 8.3 Graphical Depiction of Depreciated Structural Capacity Factor and Resulting “WITH Maintenance”

Scenario as well as “WithOUT Maintenance” effect for USFAA-ICAO Design


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Table 8.2.4 Structural Depreciation Factor for PROPOSED OPTION Reviewed Design

0

5

10

15

20

25

30

35

40

45

50

0 2 4 6 8 10 12 14 16 18 20 22

Re

sult

ing

T A



0

5

10

15

20

25

30

35

40

45

50

0 2 4 6 8 10 12 14 16 18 20 22

Re

sult

ing

T A




Maintenance” Scenario as well as “WithOUT Maintenance” effect for Reviewed Design PROPOSED OPTION


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Table 8.2.5 is a summary of the structural capacity depreciation factor, while Fig. 8.2.7 depicts the

characteristic trends of the structural capacity depreciation with time progression over the design life for

varying design options.

Table 8.2.5 Structural Depreciation Factor with Time Progression for Varying Design Options

0

5

10

15

20

25

30

35

40

45

50

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Re

sult

ing

TA


Resulting TA WITH Maintenance vs. Time

EXISTING

USFAA/ ICAO

PROPOSED OPTION (Reviewed)

Range of Design Criteria

Critical Line

0

5

10

15

20

25

30

35

40

45

50

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Re

sult

ing

TA


Resulting TA WithOUT Maintenance vs. Time

EXISTING

USFAA/ ICAO

PROPOSED OPTION (Reviewed)

Range of Design Criteria

Critical Line

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

0 2 4 6 8 10 12 14 16 18 20 22

Stru

ctu

ral C

apac

ity

De

pre

ciat

ion

Fac

tor,

fsc

Time Progression, Nt (Years)

Structural Depreciation Factor Vs. Time Progression "WITH Maintenance"

EXISTING

USAFAA/ICAO Based

PROPOSED OPTION (Review)

Critical Zone

Terminal Line

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

De

pre

ciat

ed

Str

uct

ura

l C

apac

ity

Fact

or


Depreciated Structural Capacity Factor vs. Time "WithOUT Maintenance"

EXISTING

USFAA/ ICAO

Proposed OPTION Reviewed

Critical Zone

Terminal Line


Maintenance” Scenario as well as “WithOUT Maintenance” effect for Varying Designs


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The following derivations can be made from Tables 8.2.2 ~ 8.2.5 and Figs. 8.1 ~ 8.5.

1. All Designs are adequate enough to serve the 20-years design life provided that periodic and routine

maintenance is consistently undertaken accordingly.

2. PROPOSED OPTION (Reviewed Design) exhibits the highest resistance to structural capacity

deterioration.

3. Without maintenance, the characteristic curves of all Designs will exceed the Critical Zone between

approximately 8 and 10 years, and tend to approach the Terminal Line between 11 and 14 years.

4. The most resilient design is the Reviewed Proposed Option Design, which indicates that even under

extreme conditions (excluding natural disasters such as El Nino, Earthquakes, Tsunamis, recurrent

seismic action etc), their Design Life may extend to as long as 12 ~ 14 years.

5. Consequently It can be derived that Without Maintenance there will prevail a need for intervention

to undertake Recarpeting (resurfacing). This would be approximately 11 and 13 years for the EXISTING

and US FAA/ICAO Designs and 13 to 14 years for the Proposed Designs.


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CHAPTER 9

9. METHOD OF CONSTRUCTION

General Method of Construction:

Flow Chart 9.1 Overall Method of construction


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9.1 Procedure for Construction of Ground Improved Subgrade

This procedure is to be applied to the construction of the Improved Subgrade. The technique used is the GI

technique where by the use of Moisture Control Sand Columns is applied to improve the properties of the

existing subgrade Black Cotton soils.

Flow Chart 9.2 Method of construction of the improved subgrade


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9.2 Procedure for Construction of Sub-Base/Base Course

This procedure is to be applied to the construction of the Sub-Base / Base course. We have designed for the

sub-base and base as one in this design.

Flow Chart 9.3 Method of construction of the sub-base/base course


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9.3 Procedure for Construction of Asphalt Concrete Wearing Course

This procedure is to be applied to the construction of the Asphalt Concrete Wearing Course-AC

Flow Chart 9.4 Method of construction of the Asphalt Concrete Wearing Course


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9.2 Program of Works with superimposed S-Curve

The program of works is proposed below. The comprehensive and detailed will be presented in the Detailed Design.


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9.3 Quality Control

9.3.1 Preamble

Measured and field data collection would certainly serve no purpose if appreciable accuracy and confidence

levels are not achieved. Accurate and precise definition of the boundary limits of specification control can

prove to be costly if they are not properly considered or tailored for a specific project.

The basic principles of some of the main quality control methods developed by the Author previously on other

project modified to suit the design and construction specification requirements for the Addis Ababa~ Goha

Tsion Project are briefly introduced in the subsequent sections. Numerous other interpretive methodologies,

which are not introduced in this Report, have also been developed.

9.3.2 Plasticity Materials (crushed aggregates)

This method of correction takes into account the reciprocal relation between water content (wc), density ( )

and degree of compaction (Dc).

For low plasticity materials whereby PI < 6, the following generalized quasi-empirical equations may be

applied.

100/

'

m

c

s

c

l

c

optwwwf

l

cu

cfDDw

xxCxCnww (9.1)

where, u

cfw = Moisture content correction factor for DC>100, l

cw = Moisture content determined in the

Laboratory, wfn = Constant derived from the relation between the natural and laboratory moisture contents,

C = Density correction factor for laboratory and soil variability, Cw= Correction factor for moisture content,

w= In-place wet density of soil, opt = Maximum Dry Density (MDD),s

cD =Specified Degree of Compaction,

m

cD = Measured Degree of Compaction.

For cases where Dc < 100, the following equation may be applied:

100/

1'

m

c

s

c

l

c

optwwwf

l

cL

cfDDw

xCxCnww (9.2)

L

cfw defines the moisture content correction factor for Dc < 100.

The corrected Degree of Compaction (Cor

cD ) is then given by :

s

c

w

ccfCor

cxDC

xDwD .

(9.3)


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where, .Cor

cD = Corrected degree of compaction, ul

cD = Standard upper limit degree of compaction,

C =Optimum density correction factor.

Considering some common and standard factors then, ,32.0wfn ,93.0'C 89.0wC .977.0Cand

Based on the Specifications for this Project for base course material, ul

c

s

c DandD %98 is determined as

102%. Consequently, equations (8.1), (8.2) and (8.3) are simplified to the forms expressed in Eqs. (8.4), (8.5)

and (8.6) respectively.

100/98

26.0m

c

l

c

optw

l

cu

cfDw

ww (9.4)

While,

100/98

126.0m

c

l

c

optw

l

cL

cfDw

ww (9.5)

and,

10002.1. xwD cfCorc (9.6)

Hence to correct for the aforementioned variable parameters for base course material, Eqs. (9.4), (9.5) and

(10.6) may be applied accordingly.

9.3.3 Formulae For Correction of Moisture Content Vs. Degree of Compaction for High Plasticity Materials

(Subgrade, Embankment And Sub-base)

For high plasticity materials whereby PI > 6, the following generalized quasi-empirical equations may be

applied in all cases.

100/

'

m

c

s

c

l

c

optwwwf

l

c

cfDDw

xxCxCnww (9.7)

The corrected Degree of Compaction (Cor

cD ) is then given by :

s

c

w

ccfCor

cxDC

xDwD .

(9.8)

Considering some common and standard factors ,32.0wfn 0.10.1,0.1' CandCC w

Based on the Specifications for this Project for subgrade material, ul

c

s

c DandD %95 is determined as 98%.

Consequently, Esq. (9.7) and (9.8) are simplified to the forms expressed in Eqs. (9.9) and (9.10) respectively.

100/95

32.0m

c

l

c

optw

l

cu

cfDw

ww (9.9)


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and,

10098.0. xwD cf

Cor

c (9.10)

9.3.4 Mechanical Stability Analysis

In order to analyze the impact of mechanical stability on the bearing capacity Eq. (9.11) may be adopted.

opt

II

c

r

S

opt

S

RF BRBRxRff . (9.11)

where, S

RFf = Strength Ratio Parameter, S

optf . = Strength Ratio Parameter determined at the optimum

Batching Ratio value, c

rR = Rate of Reduction of the post compaction strength , opt

IBR = Batching Ratio

Index at optimum value,

9.3.5 Quantitative Method of Evaluating Effect of Paving at Varying Grades of Slope

In developing the method of evaluating effect of paving construction in negative upgrade slope, the factors in

Table 9A were taken into consideration.

TABLE 9A

The four main influencing factors are stipulated in Table 9B.

TABLE 9B

1. Segregation of particles, flow characteristics, non-

homogeneity, contact pressure vibrational force,

consistency, tractive force, sliding, Imperfect compaction,

non-uniform thickness, impact on density, structural

deficiency, differential deformation, localized flow and

plastic failure.

2. Premature failure (cracking or micro-cracking), non-

uniform inter-particle stress distribution, development and

propagation of internal localized shear planes were also

analyzed in relation to particle size, distribution, viscosity

of bitumen, temperature, spreading rate, and state of inter-

particle contact within a bituminous medium.

1) Grade effect on the strength and shearing resistance

properties of the Asphalt Concrete

2) Damaging effect on the Marshall properties of the

Asphalt concrete

3) Effect of rate of roadway super elevation

4) Effect of excitement frequency in relation to micro-

damage initiation due to construction equipment


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Rolling Resistance (Dynamic)

Considering that,

L

VGR Crr

254

2

(9.12)

then,

100254

2

Li

VRG r

R

Cr (9.13)

where R

CrG = Critical angle of slope in relation to rolling resistance, Rr = Rolling resistance factor, V = Tractive

velocity of construction equipment and L = Compaction distance

Damaging Effect (Static)

The damaging effect on the Marshall properties of the asphalt concrete due to the critical angle of inclination

is expressed as follows.

(9.14)

where eff

sv =Damaging effect factor , lim

=Limiting grade of slope, i=Grade of slope.

Friction Factor (Dynamic)

The friction factor resulting from the dynamic component is computed as :

100127

2 e

R

VfF (9.15)

where, fF=Friction factor, V=Velocity of construction equipment, f

CVG i =Critical grade of slope in relation

to the friction factor, R=Radius of curvature

Effect of Excitement Frequency

Adopting the solution proposed by Housner (1963) for a half-sine wave acceleration pulse required for

overturning a block and modifying it to that required to initiate slip of the surface mass; then the following

equation is obtained for a value of ω that is small.

2

lim 1)(g

gap

cvs (9.16)

5.0

2

2limlim

tan1

tantantantan iieffsv


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where as=Acceleration to cause segregation, g = Force of gravity cr =Critical grade of slope, lim

=Limiting

grade of slope, p=Particle size (average), =Excitement frequency propagated by the construction

equipment.

For a large value of , Eq. (9.16) can be represented by

limlim FKgpcrgpsa

(9.17)

where, =Oscillatory velocity of construction equipment, =Angle between the hexagonal diagonal of an

ideal particle with the normal line to the slip surface with an inclination of angle θlim., KF=Contribution of inter-

particle friction factor, μ=Coefficient of friction between particle and slope.


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CHAPTER 10

10. ACCESS ROADS

There is need to design the Access Road to enable accessibility of the site and deliveries during construction.

The Access Roads can then be utilized after construction as service roads to and in the airport. From the site

investigation, the access roads are also found on problematic soils just as was the case for the airport runway

hence a more pragmatic approach of Research and Design is required in its design.

The access roads were not part of this design as the consultant was not commissioned to carry out the designs.

CHAPTER 11

11. Hydro-geological Study

The Hydro-Geological survey is very crucial to the overall design of the airport; more so the drainage

structures. We therefore propose that a comprehensive hydro-geological study be carried out. The

justification and necessity of this study is detailed in 11.1.

Note that the consultant has not been commissioned to undertake the study.

11.1 Introduction and Preparatory Work

Introduction

Drainage and environment considerations are of paramount importance to any land based project.

In the case of the project that this exercise is targeting, ‘The Rehabilitation of Isiolo Airport’, the scoping needs

to encompass the whole catchment / watershed area. Reasons for this will become evident in the justification

section.

The area in which the drainage and preliminary environmental scoping will be done will here be designated as

the ‘Focal Area’. This will include the Airport area as the core with the outlying area (watershed) as the said

‘Focal Area’.

The scoping /survey which are intended to lead to the design of the drainage system and structures will be

done with the assumption that concepts, strategies, problems, and overall solutions of the project area, have

been worked out at the appropriate decision making levels in consultation with the community / its

representatives.

Justification

The protection, improvement, and rehabilitation of watersheds are of critical importance in the

achievement of overall development goals.

Planners and implementers of projects such as the Isiolo Airport need to be aware of new approaches and

strategies in soil conservation and land management for the proper design of adequate drainage systems

and structures. This should include an awareness of issues such as farming systems analysis and

development, community forestry, etc. of the Focal area.

A project will risk being problematic and less sustainable in its future after implementation if these

considerations are not taken into account.

The drainage and environmental surveys, planning, and design for any project area will enable the

formulation of good and sustainable management strategies. The management of any project area is site

specific and no method, however sound, can be applied universally without modifying it to suit local needs.

This therefore calls for a comprehensive survey and study of every project area individually. The drainage

and environmental scoping intend to facilitate and address this need.

Survey and planning is a continuous process. This scoping / survey can be considered as a basic on which any

other future exercises can launched from or added to. Watershed management is a continuous and flexible


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process, an ongoing undertaking, this exercise is therefore very crucial to the better management and

sustainability of the project.

All watersheds contain many kinds of natural resources _ soil, water, forest, rangeland, Wildlife, minerals,

etc. In managing and developing a watershed, the use of some natural resources will be complimentary

while others will be competitive. The key, therefore, is to use these resources as efficiently and perpetually

as possible, with minimum disturbance to the watershed as a whole.

In many if not most of the developing countries, watershed degradation, and the scarce availability of

resources mandate a comprehensive, accurate, and appropriate survey and planning of any project.

In the case of the Isiolo Airport project, the drainage and environmental issues have to be approached with

utmost care. This is necessitated by a preliminary / overview study of the area’s physiography, hydro, and

geology.

The Airport project cannot therefore be developed on an exclusive basis or in seclusion. If sustainability has

to be achieved, and risks from natural disasters have to be mitigated, then the proposed focal area

/watershed survey and planning would be the most pertinent way to go.

It would be inadequate to design drainage systems and structures for the Airport without factoring in the

proposed watershed survey and planning. It would amount to creating a disaster in the name for

implementing a major development project.

The drainage of the Isiolo Airport cannot be designed without the above considerations. Some of the

pertinent questions to ask are;

o What is the source of the water to be drained?

o What is the quantity of water to be drained?

o Can the drainage system manage or accommodate the quantity?

o What are the challenges expected and from what sources?

o Can the drainage system be established economically?

o Will the drainage system be able to handle any extrapolated future discharges?

o What are the risks expected due to failure of the drainage system?

o What would be the reason(s) for the above failure?

These are some but not necessarily all the question that the proposed exercise would adequately address.

Some Objectives

Main objectives of the above exercise will be defined after collection of existing data, identifying major focal

area problems and considering management possibilities.

However there are some basic objectives for the exercise. These include:

To rehabilitate the focal area (watershed) through proper land use and conservation measures in order

to minimize erosion;

To protect, improve or manage the focal area (watershed) for the benefit of the project and resources

development;

To manage the watershed in order to minimize natural disasters such as floods, drought and landmass

movement;

To develop the watershed for the benefit of the community and the economies of the region;

Definitions

Following are some brief definitions that will be used in the scoping report.

Watershed: it is a topographically delineated area that is drained by a stream system, that is, the total

land area that is drained to some point on a waterway.


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Watershed degradation: it is the loss of value over time, including the productive potential of land and

water, accompanied by marked changes in the hydrological behaviour of a river system resulting in

inferior quality, quantity, and timing of water flow.

Watershed management: is the process of formulating and carrying out a course of action involving the

manipulation of resources in a watershed to provide goods and services without adversely affecting the

soil, water base, and other resources.

Watershed survey and planning: is the preparatory work which, if properly conceptualized and carried

out, permits the successful implementation of actual watershed management.

Focal area: is the area encompassing the core project area and the watershed.

Core project area: is the Isiolo Airport area.


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CHAPTER 12

12. Experimental Research Trial section

The experimental trial section is meant to provide us with data that give an indication of the behaviour and

performance of the different pavement configurations so that we can generate an optimum design based on

actual trafficking and loading models.

Different configurations can be generated; the following is a brief on the elementary configurations that we

propose:

Pavement with the Black Cotton Soil [BCS] as subgrade :the BCS without Ground Improvement

Pavement with OPMC without geogrids.

Pavement with OPMC with geogrids

Pavement with OBRM+Geogrids only

Pavement with OPMC + geogrids only.

OBRM+OPMC+Geogrids

The location of construction and the dimensions of the trial sections can be determined during project

implementation. 20m for each section is adequate.

The objective of the Experimental Trial Section is:

Study the loading characteristics

Intensity of loading

Mode of loading i.e. pressure distribution

Pavement response to loading, more so impact loading

Degree of performance of geogrids

Degree of stress mobilization due to the incorporation of geotextiles.

Degree and extent of Ground Improvement for BCS.


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CHAPTER 13

13. CONCLUSIONS AND RECOMMENDATIONS

13.1 Main Conclusions

In this Study presents a preliminary testing and analysis for purposes of realizing the most Value Engineering

based design for the Isiolo Airport Pavement Structure in Isiolo District.

Based on the derivations noted in this Report, the following main conclusions can be made.

1. The subgrade CBR is high when the subgrade condition is Unsoaked and the CBR values drops

tremendously when the subgrade is wet. The subgrade soil, predominantly Black Cotton Soil [BCS]

have very high amount of fines [PI of 62%]. The intrusion of the fines into the well graded base/sub-

base material should be stopped since the presence of fines will result to the increase of the capillary

action of the layer making the base vulnerable to moisture. The presence of fines will therefore lead

to the drop in strength of the pavement structure.

2. The subgrade is improved using the Ground Improvement Moisture Control Technique where sand

piles/columns are used to control moisture.

3. The gravel materials from borrow pits within the vicinity of the Project Area are suitable for the

construction of the Base Course pavement layer. The existing gravel material is porous and has

relatively low densities. We have batched the gravel with 0.6mm quarry dust to improve on its

compaction.

4. The gravel exhibit high values of strength when stabilized; chemically using cement and mechanically

using Tensar TX 170 TriAx Geogrids. Tensar TX 170G geogrids are used to mechanically stabilize the

base layer thereby enhancing the durability, longevity and versatility of the pavement. Through the

confinement of the granular material, the geogrid will maintain and improve the mechanical stability

of the pavement once the pavement structure starts showing signs of deterioration due to age and

increased passes of traffic.

5. The pavement structure is expected to exhibit increase in strength with time as the curing process

continues.

6. This pavement design reduces the overall thickness of pavement from 400mm to 200mm in

comparison to the conventional approach and cuts on the use of cement from 7-8% conventionally to

less than 3%. This design does not entail the excavation and subsequent backfilling of the Black Cotton

Subgrade Soil with selected granular Geomaterial.

7. Due mainly to the nature of the material and the existing natural ground, the magnitude of the

bearing capacity, strength and deformation resistance of the existing sub-base and subgrade

supersedes to a large extent, values specified as material requirements for base course layers by

International Agencies and Researchers.

8. The Cement-Geogrid stabilized Geomaterials exhibits higher values in terms of strength, bearing

capacity and deformation resistance as compared to the Cement stabilized materials.

9. This Design satisfies all the engineering properties and VE aspects.


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13.2 Basic Recommendations

From the foregoing analysis, discussions and conclusions, the following recommendations can be made

accordingly.

1. The GI-MC technique is meant to control moisture levels in the subgrade. It also incorporates

Geotextile/Geofabrics which will enhance the mobilization of the stresses within the Black Cotton Soil

subgrade thereby improving further the strength of the subgrade. The geofabrics will also act as a

filtration/separation membrane and will act to stop the ingress of fines into the well graded base/sub-

base granular material.

2. The inclusion of the Geogrid is of importance as can be inferred from the material analysis and conclusion.

3. From the effects of curing on the strength characteristics of the cement-geogrid stabilized Geomaterials,

the proposed pavement structure will depict increase of strength with time.

4. A comprehensive hydrological survey need to be done so as to analyze the effects of drainage and runoff

to the general operation of the airport and also design structures that will be able to control the runoff

since the proposed airport is located on a flood plain.

5. From the subgrade analysis, the access roads in and out of the airport need to be adequately designed to

enable delivery of material during construction.

6. It is envisaged that the above design [OPMC GI-MC Technique] will realize and overall saving on material

and construction time of more than 40%. This savings will come from:

a. Reduction in cement quantities from 7-8% conventionally to less than 3%

b. No excavation and subsequent backfilling of the subgrade Black Cotton Soil.

c. Reduction in construction time.


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MAIN REFERENCES

Ampadu, S.K (1988): The influence of initial shear on undrained Behavior of normally consolidated Kaolin,

Master Thesis, University of Tokyo.

Bejerrum, L., 1993. Problems of soil mechanics and construction on soft clay and structurally unstable soils

(collapsible, expansive and other). In Proc. 8th Int. Conference on SMFE, Moscow. P111~159.

Blyth, F.G.H., & de Freitas M.H>(1998) A Geology for Engineers 7th Edition. Arnold, A member of Hodder

Headline Group LONDON. SYDNEY. AUCKLAND.Bulletin of Earthquake Resistant Structure Research

Center No. 27 1994. dependence on Frequency of the Failure process of a slope Made up of Coarse

Particles. K. Konagai and T. Sato. Institute of Industrial Science University of Tokyo.

Burland, J.B. and Wroth, C.P., (1974) Review Paper : Settlement of buildings and associated damage, in

Proceeding of the Conference on Settlement of Structures, Pentech Press, Cambridge, 1974. pp.

611~654

Burland, J.B., Borroms, B.B., and De Mello, V., (1977) Behaviour of foundations and structures Proceedings of

the 9th International Conference on Soil Mechanics, Tokyo, 1977, Session 2

Burland, J.B (1990); On the compressibility and shear strength on clays and shades at constant water content,

Geotechnique, Vol. 2, PP,251.

Construction Project Consultant (1995). Tana Basin Road Development Project, Phase II Materials Report Vo. 3

Construction Project Consultant Inc., May, 2000, Hydrological Review and Analysis for Hydraulic Design of

Bridge and Major Culvert Structures and Determination of Areas of Protection, Volume I & II, Tana Basin

Road Project Phase II

Construction Project Consultant Inc., July, 2000 Engineering Report on the Design and Construction of

Reinforced Earth Embankments (The Terre Armee Method), Tana Basin Road Project Phase II.

Construction Project Consultant, 2001a. A Brief Report on the Computation of Capping Layer Thickness with

Reference to Native Subgrade Bearing Capacity, CPC Internal Report

Construction Project Consultants, 2001b. Analysis And Evaluation of the Structural Capacity and Serviceability

Level of the Existing Road Pavement (Phase III), CPC Internal Report

Construction Project Consultants, 2001c. Characterization of Black Cotton Soil as a Pavement Foundation

Material Based On Comprehensive Analysis (Stage 1), CPC Internal Report

CPC Consultants. Tana Basin Road Development Project, Phase II. Materials Report Vol. 3 Tatsuoka, F. &

Shibuya, S. Report of the institute of industrial science the University of Tokyo Vol. 37 No. (serial No.

235) (1992) Deformation Characteristics of soils and Rocks from Field and Laboratory Tests

Gidigasu. M.D. 1974a. Review of Identification of Problem Laterite Soils in Highway engineering, Transport

Research Board, Washington Recording, I, 497:96~111

Gidigasu. M.D. 1988. Potential application of engineering pedology in shallow foundation engineering on

tropical residual soils. In Geomechanics in Tropical Coils. Proc. of the II Int’l Conference on Geomechanics

in Tropical Soils, Singapore, 1,17~24.

Gono, k., Mukabi, J.N., Koishikawa, K., Hatekayama, R., Feleke G., Demoze W., Zelalem A., (2003a).

Characterization of Some Engineering Aspects of Black Cotton Soils as Pavement Foundation Materials,

to be published in the proceedings of the International Civil Engineering Conference on Sustainable

development in the 21st Century.

Hansen, J. Brinch, (1968) A revised extended formula for bearing capacity, Danish Geotechnical Institute Bulleti

No. 28 and code of Practice for Foundation Engineering Denish Geotechnical Institute Bulletin No. 32

(1978)

Hardin, B.O and Drnevich, V.P. (1972), Shear-modulus and damping in soils : measurement and parameter

effects, Jouranl of the Soil Mechanics and Foundations Division, ASCE, Vol. 98, No. SM6:603-624


Page 180

© 2

01

0/2

011

Ken

setsu

Ka

ih

atsu

Lim

ited

Horii, N., Toyosawa, Y.& Ampadu, S.K Undrained shear characteristics of soft clay after cyclic loading .pp.

113~118.Housner, G. W.: The Behavior of Inverted Pendulum Structures During Earthquakes, Bull. of the

Seismological Society of America, Vol. 53, No. 2, pp. 403-417, 1963.

Honsen, J. Brinch, (1961) A general formula for bearing capacity, Danish Geotechnical Institute Bulletin No. 11

Imad L.Al-Qadi, Gerardo W. Flintsch, Amara Loulizi, Samer Lahouar & Walid M. Nassar Pavement

Instrumentation Responses at the Virginia Smart Road. IRF Road World Congress, Paris, June 2001.

Japan Road Bureau, Japan. 1993. In Road Design Manual, Vol. I (in Japanese).

Jardine, R.J. 1985. Investigations of pile-soil behavior, with special reference to the foundation of offshore

structures. PhD Thesis, University of London.

JICA Study Team, 1999. The Study on Rural Roads Improvement In Western Kenya-Materials Testing Analyses

and Countermeasures for Design Purposes, Feasilibility Study by The Government of Japan And The

Government of Kenya.Jardine, R.J. (1995): One perspective of the pre-failure deformation characteristics

of some Geomaterials, IS Hokkaido’ 94,2,pp.855-885.

Konagai1 Kazuo and Sato2 Takeshi. Dependence on Frequency of the Failure Process of Slope Made up of coarse

Particles. pp. 33~39

K.J. McManus, G. Lu and D. Ruan, The Effects on a Bridge Superstructure of Dynamic Loads Generated by Long

Wavelength Roughness in Road Surfaces. IRF Road World Congress, Paris, June 2001.

Meyerh of, G.G., (1963) some recent research on bearing capacity of foundations, Canadian Geotechnical

Journal, 1, 16-26.

Ministry of Transport & Public Works, Kenya, 1981. Materials and Pavement Design for New Roads. In Road

Design Manual Part III.

Ministry of Public Works & Housing Republic of Kenya, March 1999. Report to OECF Appraisal Mission for the

Additional Loan to “Tana Basin Road Project” in the Republic of Kenya, Volume I & II.

Mukabi, J.N.(1991): Behavior of clays for a wide range of strain in Triaxial compression, Msc. Thesis, University

of Tokyo.

Mukabi, J. N. (1995): Deformation Characteristics of small strains of clays in triaxial tests PhD Thesis, Univ. of

Tokyo. Mukabi, J.N. (1998):Con-Aid Research and Development Proposal.

Mukabi.,J.N., Murunga P.A, Wambura.J.H. & Maina J.N., Behavior of con-Aid treated fine grained Kenyan soils.

Geotechnics for Developing Africa, Wardle, Blight & Fourie (eds) 1999 Balkema, Rotterdam, ISBN 90 809

082 5.pp.583~519.

Mukabi J.N & Tatsuoka, F. 1995. Effects of swelling and saturation of Unsaturated Soil Behaviour and

Applications, Int. Symposium on the Behaviour of Unsaturated Soils, University of Nairobi, Nairobi, Kenya.

Mukabi J.N & Tatsuoka, F., Kohata, Y. & Akino, N. 1994b. Small strain stiffness of Pleistocene clays. Proc.

Int.Symp. on pre-failure Deformation Characteristics of Geomaterials, IS-Hokkaid. ‘94’ Balkema, Vol. 1, PP.

189-195

Mukabi J.N & Tatsuoka, F. (1992); Effects of consolidation stress ratio and strain rate on the peak stress ratio of

Kaolin, the 27th Annual meeting of the JSSMFE, Kochi, PP.655~6

Mukabi J.N. & Tatsuoka, F. (1994); Small strain behavior in triaxial compression of lightly over consolidated

Kaolin, proc. 49th Annual Conf. Of JSCE, III, pp.296~297Mukabi J.N & Tatsuoka, F. 1999. Effects of stress

path and ageing in reconsolidation on deformation characteristics of stiff natural clays. Proc. 2nd I.S on pre-

failure characteristic of Geomaterials, Torino.

Mukabi, J.N 1999. The Study on Rural Roads Improvement in Western Kenya – Materials Testing Analyses and

Countermeasures for Design Purposes. In Internal Reports and Correspondence, Japan International

Cooperation Agency (JICA) & Ministry of Roads & Public Works, Kenya.

Mukabi, J.N. 2000. The design and construction of Reinforced Earth Embankments. In Internal Reports and

Correspondence, The Terre Armee Method, 2000. CPC, Nairobi.


Page 181

© 2

01

0/2

011

Ken

setsu

Ka

ih

atsu

Lim

ited

Mukabi, J.N & Tatsuoka, F. 1994, 1999. Small strain behaviour intriaxial compression of lightly over-consolidated

Kaolin. In Proc. 49th Annual Conf. of JSCE, III: 286-297. Influence of reconsolidation stress history and strain

rate on the behaviour of kaolin over a wide range of strain. In Wardle, Blight & fourie (eds), Geotechniques

for Developing Africa: Proc. 12th African Regional Conf. ISSMGE Durban, 1999. Balkema, Rotterdam.

Mukabi, J.N. 2001a. Theoretical and empirical basis for a method of determining the optimum batching ratio

for mechanical stabilization of Geomaterials. In Proc. 14th IRF road World Congress, Paris, June 2001.

Mukabi, J.N & Shimizu, N. 2001b. Strength and deformation characteristics of mechanically stabilized road

construction materials based on a new batching ratio method. In Proc. 14th IRF Road World Congress,

paris, June 2001.

Mukabi, J.N. Njoroge, B.N. & Toda, T. 2001c. pragmatic method of evaluating design parameters adopting

Kenyan tropical soils for pavement structure, In Procl 4th IRF Road World Congress, Paris, June 2000.

Mukabi, J.N, 2001d. Derivation and application of consolidation and shear stress ratio functions with reference

to Critical State analysis of N.C clays. In Proc. ISSMGE Istabul International Conference. August 2001.

Mukabi, J.N., 2002c. Some Recent Advances in highway and bridge foundation engineering, Seminar for

Ethiopian Roads Authority and Japan Overseas Development Assistance Ethiopia.

Mukabi, J.N., Gono K., Koishikawa K., Feleke G., Hatekayam H., Demoze W., R., Kunioka H., Zelalem A.,

(2003a). Innovating Modified NDT/DT Techniques for the Evaluation of An Existing Pavement Structure-

Method of Testing, to be published in the proceedings of the International Civil Engineering Conference

on Sustainable development in the 21st Century.

Mukabi, J.N., Gono K., Koishikawa K., Feleke G., Hatekayam R., Demoze W., Kunioka H., Zelalem A., (2003b).

Innovating Modified NDT/DT Techniques for the Evaluation of An Existing Pavement Structure-

Theoretical Considerations and Experimental Results, to be published in the proceedings of the

International Civil Engineering Conference on Sustainable development in the 21st Century.

Mukabi, J.N., Feleke G., Demoze W., Zelalem A., (2003c). Impact of Environmental Factors on the

Performance of Highway Pavement Structures, to be published in the proceedings of the International

Civil Engineering Conference on Sustainable development in the 21st Century.

Newill, R.J. (1961). A Laboratory Investigation of Two Red Clays from Kenya, Geotechnique, 11(4)

302~318.Pandian, N.S., Nagaraj, T.S. & Sivakumar Banu, G.L (1993). Tropical Clays, Part II. Engineering

behaviour. J. Geotech. Engrag., ASCE.

Peck, R.B., Hanson, W.E. & Thornburn, T.H 1967. (2nd ed) Foundation Engineering, 271-276. New York, John

Wiley.

Richart, Jr., F.E. (1977); Dynamic stress-strain relationships for soils, S-SO-A ,Proc. Of 9th ICSMFE, Tokyo, 3,

pp.189-195.

Road Research. Catalogue of road surface deficiencies. 1978 Organization for economic cooperation and

development. Road Research Institute. MOC, Japan. 1990 Specifications for road and bridge design, Vol.

I & IV. (in Japanese)

Road Research Laboratory, 1970. A guide to the structural design of pavements for new road. Road Note No.

29.

Road Transport Research. Pavement Management Systems. Paris, 1987 Organization for economic

cooperation and development.

Skempton, A.W and MacDonald, D.H. (1956), The allowable Settlement of buildings, Proceedings, of the

Institution of Civil Engineers, part 3, 5, 727-784

Savage, P.F. & Leou, J. (1998). Guidelines on Use of CON-AID Liquid Chemical Stabilizer.

Savage, P.F. (1998). Some Experiences on the Use of Con-Aid: A Water-Soluble Ionic Additive, University of

Pretoria.Tatsuoka Fumio, Lo Presti Diego and Kohata Yukihiro, April 2-7, 1995, Third International

Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics.


Page 182

© 2

01

0/2

011

Ken

setsu

Ka

ih

atsu

Lim

ited

Shultze, E. and sheriff, G., Prediction of Settlement from evaluated settlement observations for sand,

Proceedings of the 8th International Conference on Soil Mechanics, Moscow, 1973, Vol. 1, pp. 225.

Tatsuoka, F, Jardine, R. J., Lopresti, D., Benedetto, D. H. and Kodaka, T. (1997). Characterizing the pre-failure

Deformation Properties of Geomaterials, Theme lecture ICSMFE, Hamburg, vol. 4. pp.2129-2164.

Tatsuoka, F. 1992 Roles of facing rigidity in soil Reinforcing, Theme Lecture for International Symposium,

Kyushu,Japan.

Tatsuoka, F, Jardine, R. J., Lopresti, D., Benedetto, D. H. and Kodaka, T. (1999). Characterizing the pre-failure

Deformation Properties of Geomaterials, Theme lecture ICSMFE, Hamburg, 1997, vol. 4. pp.2129-

2164.2,pp.947-1063.

Tatsuoka, F. and Kohata, Y. (1995): Stiffness of hard soils and soft rocks in engineering applications, Keynote

Lecture, IS-Hokkaido ’94,Vol.

Terzaghi, K. & Peck, R.b 1967. (2nd ed) Soil Mechanics in engineering practice, 310. New York, John Wiley.

Towhata, I., Kawasaki, Y., Harada, N. & Sunaga, M. Contraction of soil subjected to traffic-type stress

application. Proc. Int. Symp. On Pre-failure Deformation Characteristics of Geomaterials, IS-Hokkado 94,

Balkema Vol. 1, pp. 305~310.

Transport and Road Research Laboratory. 1977. A guide to the structural design of bitumen surfaced roads in

tropical and sub-tropical countries. Road Note No. 31Vanghn, P.R. 1985. Geotechnical Characteristics of

residual soils. In J. Geotech. Engrg. ASCE, III(1) 77~94. Yoder, E.J & Witczak, M.W; (1975). Principles of

Pavement Design Second Edition, A Wile-Interscience Publication-John Wiley-Sons, Inc.

MAIN REFERENCES

Annex 14 Volume of the International Civil Aviation Organisation

International Civil Aviation Organization (ICAO) Standards and Procedures for Aerodromes Design

US Army Corps of Engineers and Federal Aviation Administration (FAA) Design Method

737 Airplane Characteristics – Airport Planning – Boeing Commercial Airplane Company