2015. 11. 21

Land & Housing Institute

Jung, Jong Suk

2015 Maine Stormwater Conference

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CONTENTS

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Introduction

1. Measurement of quantity of water infiltration into road substructure

through infiltration swale

2. Evaluation of pavement performance due to water infiltration into road

substructure

Background

Possibility of pavement structure weakness due to water infiltration though infiltration swale

Objectives

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Research Approach

1. Mockup Structure Test

- 10m length*3m width road with swale(l0m length*width 1m)

- Artificial rainfall

2. Real Structure

- 6m width real road with swale

- natural rainfall

Structural and Water Flow Analysis

Mockup and Real Structures Tests

1. Water Flow Analysis(Vadose/W FEM Program)

- Analysis of water content ratio at subbase and subgade of road due to

water infiltration through swale

2. Road structural Analysis(Kenpave FEM Program) :

- Damage analysis of substructure due to change of water content ratio

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Water Flow Analysis

Input Date of Road and Swale

Initial water content ratio

Classification ThicknessWater content ratio, coefficient of

permeability

Base 140mm Road Base (Class 6)

Subbase 160mm Brooks and Corey model

Anti-Frost heave Layer 520mm Brooks and Corey model

Subgrade 480mm Uniform Sand

Infiltration trench 1350mm Porous aggregate

Classification Road Infiltration swale

Width 3000mm 1000mm

Infiltration swale

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Climatic Conditions of Cases

1. Assume average climatic conditions of Korea

2. Analysis on water flow of 5 cases classified by range of rainfall and time

Water Flow Analysis

CaseTemperature(

°C)

Humidity

(%)

Rainfall

(mm)

Range of time

(hr)

Evaporation

(mm/day)

Case 1 15 60 60 12 5

Case 2 15 60 90 12 5

Case 3 15 60 100 12 5

Case 4 15 60 100 24 5

Case 5 15 60 100 48 5

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Results of Water Flow Analysis

1. After 20 hours, Case 3 reaches maximum water content ratio of 43%(fig 1)

2. Water content ratio of 40% at subgrade is continued for 10 days(fig 2)

3. After 55days, initial water content ratio is recovered (fig3)

Water Flow Analysis

Fig 1. water content ration and water flow after 20 hours

Fig 2

Fig 3

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Trends of Water Flow and Change of Water Content Ratio by Time

Water Flow Analysis

Fig 1. after a day

Fig 2. after 3 days

Fig 3. after 6 days

Fig 4. after 50 days

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Conclusion of Water Flow Analysis(1)

1. All cases reach saturating condition, except for case 5

2. Case 3 shows the fastest arrival time of maximum water content ratio

3. Case 4 shows the latest recovery time of initial water content ratio, the longest continuous time over water content ratio of 40%, and the widest area over water content ratio of 40% at subgrade

Water Flow Analysis

Items Case1 Case2 Case3 Case4 Case5

Maximum water content ratio 42% 43% 43% 43% 35%

Arrival time of the maximum water

content ratio23hour 22hour 20hour 23hour 48hour

Continuous time over water content of 40% 48hour 60hour 240hour 310hour -

Recovery time of initial water

content ratio35day 45day 55day 60day 20day

Area over water content ratio 40%

(subgrade)

0.0271m2 0.0673m2 0.2011m2 0.3026m2 -

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Conclusion of Water Flow Analysis(2)

1. Case 1, 2, and 5 have not much influence on water infiltration though swale

2. Considering continuous time over water content ratio of 40%, recovery time of initial water content ration, area over water content ratio of 40% at subgrade- Case 3 and 4 may have influence on pavement performance by water

infiltration through swale

3. As shows result of case 4, low continuous rainfall have more influences change of water content ratio than that of short intense rainfall

4. According to results of water flow analysis of case 3 and 4, rainfall of100mm/day may have bad influence on pavement performance

Water Flow Analysis

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Input Date(1)

Pavement Performance Analysis

layer Thickness Possion Ratio E(psi)

Surface 50 mm→2.0 in 0.3 300,000

Base 140 mm → 5.5 in 0.3 200,000

subbase 160 mm → 6.3 in 0.35 21,030

Anti-Frost heave Layer 520 mm → 20.5 in 0.35 21,030

subgrad 0.4 16,128

Input Date(2)

1. Experiment of physical characteristics on sublayer at mockup and real road site- Resilient Modulus of subbase : 145Mpa- Resilient Modulus of subgrade : 111.2 Mpa

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Estimation of Modulus of Electricity by Change of Water Content Ratio

Pavement Performance Analysis

1. Initial modulus of electricity of subgrade- 111.2 Mpa = 16,128psi

2. Modulus of electricity of subgrade after raining- 30.15Mpa = 4373psi

E = modulus of electricityEopt = modulus of Electricity at initial water content ratioW = water content ratio after rainningW = water content ratio at initial water content ratio

VMC = volumetric moisture contentGMC = gravimetric moisture contentrd = dry unit weight of soilrw = dry unit weight of water

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Result of Pavement Performance Analysis(1)

Pavement Performance Analysis

RADIALCOORDINATE

VERTICALCOORDINATE

VERTICALDISPLACEMEN

T

VERTICALSTRESS(STRAIN)

RADIALSTRESS(STRAIN)

TANGENTIALSTRESS(STRAIN)

SHEARSTRESS(STRAIN)

0.00000(STRAIN)

7.50000 0.0149717.598

3.041E-04-72.043

-2.785E-04-72.043

-2.785E-040.000

.000E+00

0.00000(STRAIN)

34.30010 0.006422.353

1.468E-04-0.018

-5.904E-05-0.018

-5.904E-050.000

.000E+00

AT BOTTOM OF LAYER 2 TENSILE STRAIN = -2.785E-04

ALLOWABLE LOAD REPETITIONS = 1.185E+06 DAMAGE RATIO = 3.207E+00

AT TOP OF LAYER 4 COMPRESSIVE STRAIN = 1.468E-04

ALLOWABLE LOAD REPETITIONS = 1.980E+08 DAMAGE RATIO = 1.919E-02

1. Initial modulus of Electricity = 16,128psi

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Pavement Performance Analysis

RADIALCOORDINATE

VERTICALCOORDINATE

VERTICALDISPLACEMENT

VERTICALSTRESS(STRAIN)

RADIALSTRESS(STRAIN)

TANGENTIALSTRESS(STRAIN)

SHEARSTRESS(STRAIN)

0.00000(STRAIN)

7.50000 0.0160717.245

3.06E-04-73.294

-2.82E-04-73.294

-2.82E-040.000

.000E+00

0.00000(STRAIN)

34.30010 0.012341.272

3.01E-04-0.054

-1.24E-04-0.054

-1.24E-040.000

.000E+00

AT BOTTOM OF LAYER 2 TENSILE STRAIN = -2.824E-04

ALLOWABLE LOAD REPETITIONS = 1.133E+06 DAMAGE RATIO = 3.355E+00

AT TOP OF LAYER 4 COMPRESSIVE STRAIN = 3.008E-04

ALLOWABLE LOAD REPETITIONS = 7.974E+06 DAMAGE RATIO = 4.766E-01

Result of Pavement Performance Analysis(2)

1. Modulus of electricity after raining = 4,373psi

Conclusion of Pavement Performance Analysis

1. When compared initial water and content ratio after raining, - allowable load repetitions =1.185E+06 and 1.133E+06

(4.38% difference)2. Infiltration water though swale does not much influence on pavement

performance

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Mockup and Real Structures Tests

Mockup Structure Test

Location of sensor Infiltration

Swale

Sensor and Dater logger

InfiltrationSwale

subgrade

subbase

base

surface

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Real Structure Test

subgrade

subbase

base

surface

InfiltrationSwale

Sensor failure

SWALE

ROAD

sw

ale

road

should

er

sid

ew

alk

Mockup and Real Structures Tests

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Measurement of Initial Water Content Ratio

Initial water content ratio(%)

subgrade

subbase

base

surface

InfiltrationSwale

InfiltrationSwale

subgrade

subbase

base

surface

②

①③

④

Sensor location

After construction

After 9days

① 33.0% 32.2%

② 32.8% 32.3%

③ 37.8% 37.7%

④ 35.0% 34.3%

Fig 1. Mockup structure

Fig 2. Real structure

Mockup and Real Structures Tests

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Future Plan

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THANK YOU