control of embankments construction by observing lateral by dr. malek smadi of geotill

Embankment

Soft Clay

CONTROL OF

EMBANKMENTS

CONSTRUCTION BY

OBSERVING

LATERAL

DEFORMATION

Malek Smadi, Ph.D., P.E.

Principal Engineer - GEOTILL

Fishers, Indiana

[email protected] - www.geotill.com

GEOTILL, Inc.

http://www.geotill.com/

Malek Smadi Ph.D., P.E.

Statement of the

Problem

AS

U AD

Dm St

ZI t, g

B

L

Lo

h

L c

Ds

Sd Su

b

z

Zm

b

Evaluating and comparing entire ground

deformations allows the prediction of ground

failure during embankment construction.


Statement of the

Problem

Organic Soil Layer


Statement of the

Problem


Undrained shear Deformation

depends on:

Soil profile

Nature of soil deposits

Type of structure

Rate and method of construction


Evaluation of the Undrained

Settlement of Structures on

Clay Is Important Because:

Undrained settlement may

constitute a large portion of the

total final settlement

Undrained settlement is closely

related to the undrained stability

of a foundation


Behavior of Clay Foundation

Subjected to Embankment

Loading

sp

Ds

D

u

Time

Time

Time

Time


Observations of Behavior of

Trial Embankment during

Construction

gH, kPa

0 10 20 30 40 50 60 70

Excess P

ore

Pre

ssu

re

Du

, kP

a

0

10

20

30

40

50

60

70

FP\

s p - s vo

= 22 kPa

B2 = 0.98

B3 =

2.5

B1 = 0.63

gH, kPa

0 10 20 30 40 50 60 70

Sett

lem

en

t S

t a

nd

Maxim

um

Late

ral

Defo

rma

tio

n D

m,

cm 0

10

20

30

40

50

60

70

Pause in constructionfor 2 days

St

DuDm


Compilation of Observed Pore

Pressure in Clay at the Beginning of

Embankment Construction

0.0 0.2 0.4 0.6 0.8 1.0z/

ZI

0.0

0.2

0.4

0.6

0.8

1.0

+-D

mean

Dsv

Du


Typical Du = ƒ (Dsv)

Relationship

Dsp - Dsvo

F

P

Dsv critical

Dsv critical

Due

Applied Vertical Stress Dsv = I (gH)


Computed Total Stress vs.

Measured Excess Pore Water

Pressure

(Dsv) Computed, kPa

0 20 40 60 80 100 120

Du

) M

ea

su

red

, kP

a

0

20

40

60

80

100

120O

Ska Edeby

Changi

Chek Lap Kok


Effective and Total Stress

Paths under the Center of an

Embankment


Deformation of the Ground

under an Embankment

Using Lateral Deformation as a Measure of

Undrained Stability


The Relationship between the Depth

of the Maximum Lateral Deformation

and the Depth of Lateral Deformation

Influence

ZI, m

0 10 20 30 40 50 60

Zm

, m

0

10

20

30

40

50

60

Zm = 0.3 ZI


The volume of soil that displaces horizontally

is related to the volume of soil that displaces

vertically. Therefore, the progress of lateral

deformation with time can be estimated using

the equations:

Deformability

Factor

Where:

a = Deformability Factor

AD = a AS (t)

Dm = a St (t) OR

StDm


Deformability

Factor

The deformability factor is a

function of:

Geometry of embankment

Drainage conditions

Properties of foundation clay

which will vary with time


Deformability

Factor Values

Deformability factor, has different values

corresponding up to five periods during the life of an

embankment:

From beginning of construction to the yield point

From the yield point to end of construction

From beginning of construction to end of

construction

From end of construction up to five years

From five years to very long term


Canvey Island Tank 4352; Vertical Volumetric Displacement Vs Lateral Volumetric Displacement

Vertical Volumetric displacement VV (m3)

0 400 800 12000

40

80

120

160

VH

Vv

= 14.5%

Ho

rizo

nta

l V

olu

me

tric

Dis

pla

cem

en

t V

H (

m3)


I-95 Sec 246, Boston

Soil Profile

Water Content (%)

20 40

D/Dm

0.0 0.2 0.4 0.6 0.8

Z/Z

I

0.0

0.2

0.4

0.6

0.8

1.0

Dm = 10.9 cm

ZI = 44 m

Medium fine sand

Stiff boston blue clay

Soft boston blue clay

Medium boston blue clayOCR from 9 to 1

N = 20

Undrained Shear Strength su (Fv) (kpa)

20 40 60

Vertical Sttesses

s'vo, s'p and

sv' (EOC) (kpa)

0 200 400

s'vo

s'p

(EOC)

s'vo

+ Dsv

620 day ( EOC)

473 day375 day

570 day2000 day

N = 10


I-95 Sec 246 Lateral Deformation

Vs Total Settlement

St (cm), at the center

0 10 20 30 40 50 60 70 80

Dm

(cm

), a

t th

e toe

0

4

8

12

16

20

375 day

620 day

(End of construction)

473 day

2000day0.19

0.54

0.27

0.19


Relationship between the Maximum Lateral Deformation and the Settlement after the End of Construction under Seven Embankments

DSt, Consturction Settlement, cm

0 20 40 60 80 100

DD

m, M

axim

um

Late

ral

Defo

rmation

0

5

10

15

20

25

DDm = 0.16 DSt

Cubzac B

Provins

Palavas, with drains

Palavas, without drain

St. Alban B

Drammen II

Ska Edeby VIo


Deformability

Factor Values

From beginning of construction to the yield

point (represent overconsolidated states at

the beginning of banking) :

Dm = 0.22 St

StDm


Deformability

Factor Values

From the yield point to end of construction

(represent normally consolidated states at the

completion of embankment construction):

Dm = 0.71 St

StDm


Deformability

Factor Values

From end of construction up to five years

(where consolidation is dominant):

Dm = 0.17 St

StDm


Deformability

Factor Values

From five years to very long term (increased

significance of secondary deformations)

Dm = 0.07 St

StDm


Factor of Safety Vs (Lateral Deformation/Shear Modulus)

Factor of Safety

0 1 2 3Late

ral

Defo

rmati

on

(cm

)/S

hear

Mo

du

lus (

kp

a)

0.0001

0.001

0.01

0.1 1 Gardiner Dam2 I-95 Sec 2463 Portsmouth4 New Liskeard5 Gloucester Test Embankment6 Fukuyama7 Sakura8 Nagareyama9 Hazama10 Toichi11 Isehara12 Uenodai 13 Ska Edeby Test Emankment VI14 Hachirogata15 Takezato16 Toyooka 117 Toyooka 218 Canvey Island Tank 435219 Kalix (Failed)20 Natal Coast Embankment21 Debris Dike (Failed)22 Stoegersbachdamm Road Embankment23 James Terminal Facility Tank 624 James bay Test Embankment25 Olga C zone A26 Olga C Zone C27 Deep Seated Base Failure of an Embankment28 Genesee South Fill29 Highway 97


Dm/St Vs St Diagram for Prediction Failure

Dm/St

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

St

,m

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Yaizu (STA884)

Fukuroi

Tsukisappu

Aiko

Koisegawa

Chiba-A

Chiba-D

Tamajima-2Kure

Fukuroi (C)No-219

Tsurikawa-Bashi

Fukuroi (N)

Koda

Yaizu (STA876+20)

Yaizu (STA882)

Tamajima-1Saga

FailureNon FailureFailure Curve

StDm


Control of Embankment

Construction

This method has been used for monitoring

the factor of safety during construction by

observing vertical settlement at the center

under an embankment and the horizontal

displacement near the toe of the slope

Using this method most of the embankments

failed near the curve that separates stable

from unstable conditions

Malek Smadi Ph.D., P.E. Control Chart

Dm/St

0.0 0.4 0.8 1.2 1.6

St

, m

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Observed Data

q/qf = 1.0q/qf = 0.9 - 0.99q/qf = 0.8 - 0.89q/qf = 0.7 - 0.79q/qf = 0.6 - 0.69

1.0

(FS

= 1

.0)

0.9

(1.1

)

0.8 (1.3)0.7 (1.4)

0.6 (1.7)

Malek Smadi Ph.D., P.E. Control Chart

Dm/St

0.0 0.4 0.8 1.2 1.6

St , m

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

1.0 (FS = 1.0)

0.9 (1.1)

0.8 (1.3)0.7 (1.4)0.6 (1.7)

4

32

1

B

A

Tokyo Bay Coastal Road EmbankmentBefore point A, Banking 5.0 cm/day

Between point A & B, Banking 9.0 cm/day

After point B, Banking 3.8 cm/day

Whitewall Creek

1 End of first lift

2 End of first consolidation stage

3 End of second lift

4 End of second consolidation stage

Koda Embankment

Failure Line

Malek Smadi Ph.D., P.E. Conclusions

The values of adeformability factor) for

Dm were in the range of 0.17 from the end of

construction to 5 years, to 0.71 from yield

point to end of construction.

These factors could be used to estimate

behavior of lateral deformation from

settlement observations in the absence of

inclinometers across the embankment.

Malek Smadi Ph.D., P.E. Conclusions

Dm/St versus St plot can be used to

monitor the degree of safety during

embankment construction.

StDm


Dr. Malek Smadi, P.E.

Principal Engineer - GEOTILL

Fishers, Indiana

[email protected]

www.geotill.com

Questions ?

http://www.geotill.com/

control of embankments construction by observing lateral by dr. malek smadi of geotill

Engineering