Effect of Temperature and Water Content on Creep …cem.uaf.edu/media/96512/Creep-of-Grouted-Anchor.pdf1 Effect of Temperature and Water Content on Creep behavior of Grouted Anchors

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Effect of Temperature and Water Content on Creep behavior of Grouted Anchors

Chuang Lin, Liangbiao Chen and Xiong Zhang

University of Alaska Fairbanks

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Outline

Introduction

Literature Review

Experimental Work

Data Analysis

Conclusions

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3

Research Background

(From Vinson and McHattie , ADOT&PF file 2009,)

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4

Grouted Anchors

a) b) c)

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5

Basis Creep Behavior

I:Primary

Dis

plac

emen

t, u

Time, t

II:Secondary

III:Tertiary

P

u

5

Vyalov, 1966; Biggar and Kong, 2001

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Creep Equation

13

)1(

n

aBu

na

n

a

n and B : soil parameters a, anchor radius

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Johnston and Ladanyi, 1972

Morgenstern et al., 1980

Temperature, oC n B (kPa-n year-1)

-1 3.0 4.50×10-08 -2 3.0 2.00×10-08 -5 3.0 1.00×10-08 -10 3.0 5.60×10-09

no slip

Morgenstern et al. (1980)

Graph

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10-3 10-2 10-1 100 101 102101

102

103

oC-1-2-5

Shea

r Stre

ss, k

Pa

Normalized Displacement Rate, u/a, year-1 .

-10

The Existing Design Guidelines Morgenstern et al. (1980)

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We are parallel!

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Anchor Load Tests

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“pile load test is …. the best means for checking the validity of theoretical prediction”

Andersland and Ladanyi , 2004

A B

C D

Sustained-load tests Staged-load tests Economic

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Literature of Load Tests

Types Soil Description

Temp. oC n B

(kPa-n year-1) Sources

Grouted anchors

M.C.=20%~50% -0.56 8.1 3.96×10-13 Johnston and Ladanyi,1972 M.C.=20%~60% -0.28 7.5 5.18×10-12

Pile Saline Ice-rich soils

-5 3.0 1.64×10-6 Nixon and Neukirchner 1984 -10 3.0 2.54×10-8

Grouted Piles

Saline Ice poor soils -5 9.3 1.69×10-25 Biggar and Sego1994

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(Biggar and Kong, 2001) Temp.

oC n B (kPa-n year-1)

-1 3.0 4.50×10-08 -2 3.0 2.00×10-08 -5 3.0 1.00×10-08

-10 3.0 5.60×10-09

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Literature Summary & Task 2

◦ Creep, Secondary Creep ◦ Theory & Guidelines

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Task 1

Task 2 ◦ Anchor Load Test

◦ Ice-rich silt ◦ Grouted anchors

Load Test

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Load Test Overview

•In laboratory •Warm temperature • ua, , and T

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Test setup in 3D

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13

Anchor placement

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a. Ff =700 lbs b. Ff =3000 lbs

Final Version

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True pictures

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Barrel

Silt Remolding Load Frame & Steel Plates

Test Anchor

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Pictures

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Test Arrangements

16 7.6'

2.5'

1.6

2.75'

14.9'

6.2'

Free

zer C

ore

Length Unit : Foot

4.8

Control Panel

7.3'

M. C. = 50%

M. C. = 120%

M. C. = 80%Load Frame A

Load Frame B

Load Frame C

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Test Summary

19 anchor load tests 26 data points (ua, , and T)

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Pullout Failure Pattern

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4”

1.5”

g< 2% Shear Strength not reached! Soils

2”

0.04”

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0 200 400 600 800 1000 12000

5

10

15

20

a

dc

e

a. =5.3 psi,-1.1~-1.8oCb. =7.3 psi,-1.2~-1.9C

d. =11.3 psi,-1.3~-2.0oCc. =9.3 psi,-1.2~-1.8oC

W.C.=120%

e. =13.3 psi,-1.3~-2.0oC

Cre

ep D

ispl

acem

ent,

0.00

1 in

ch

Time, Minutes

b

Example of Creep Curves

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-1.1

-1.8

damped

average

well defined

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Test data Test # Average Temp.,

oC

Normalized Displacement Rate,

/a, year-1 Shear stress, kPa Creep

Pattern

50% -0.4 2.996 34.5 3 50% -0.7 2.497 65.5 3 50% -1.2 2.628 113.1 3 50% -1.4 0.946 91.0 3 50% -2.3 0.263 126.9 2 80% -0.4 68.328 48.3 3 80% -0.6 6.570 33.1 3 80% -0.7 3.154 63.4 3 80% -0.8 0.158 20.7 2 80% -1.2 0.289 37.9 2 80% -1.2 1.761 71.0 3 80% -1.3 0.762 81.4 3 80% -1.3 0.263 55.2 2

120% -0.1 215.496 20.7 3 120% -0.4 5.782 34.5 3 120% -0.8 19.710 68.9 3 120% -0.8 0.263 34.5 2 120% -1.0 1.314 46.9 2 120% -1.0 39.420 69.6 3 120% -1.4 0.263 34.5 2 120% -1.4 0.263 48.3 2 120% -1.4 1.577 63.4 2 120% -1.4 3.942 77.2 3 120% -1.6 0.420 77.9 2 120% -1.6 2.547 91.7 3 120% -1.2 0.184 20.7 2

au

50%

80%

120%

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Comparisons with Design Guidelines

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10-4 10-3 10-2 10-1 100 101 102 103100

101

102

103

104

-2oC

Shea

r Stre

ss, k

Pa

Normalized Displacement Rate, u/a, year-1

-1oC

.

<

T=-1.0~-2.0oCT=-2.3oC

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Regression Model

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13

)1(

n

Bau

na

n

a

n

aw

maa

uT

/1

)(

m (kPaw) , creep modulus w, temperature exponent n, stress exponent

( i, ua,i, Ti ) + M. C.

Test data:

T ?

a

n

na

u

a

n

B

13

)1(

a

na

u

aTf

)(

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Regression Results

M.C. m(kPaw) w n R2 SE (kPa) 120% 43.38 0.87 6.08 0.78 10.9 80% 53.57 1.27 3.90 0.67 11.7 50% 70.93 1.08 3.91 0.98 5.62

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n

aw

maa

uT

/1

)(

SE, Standard Deviation of Error

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Effect of Moisture Content

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10-3 10-2 10-1 100 101 102 103100

101

102

103

T=-1oC80%50%

120%

Shea

r stre

ss, k

Pa

Normalized Displacement Rate, u/a, year-1 .

50% 80%

120%

<

<

Same order!

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Effect of Temperature

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10-3 10-2 10-1 100 101100

101

102

103

-1 oC -2 oC -3 oC

Shea

r Stre

ss, k

Pa

Displacement Rate, (ua/a), year-1.

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Developed Design Guidelines

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-0.5 -1.0 -1.5 -2.0 -2.50

20

40

60

80

100

12008.6/1

87.0)(67.45

a

uT a

1 year-1

0.1 year-1

0.01 year-1

Shea

r Stre

ss, k

Pa

Temperature, oC

0.001 year-1

M.C.=120%

SE=10.9 kPa

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Conclusions

Laboratory tests performed to evaluate influence of

temperature and moisture content

Existing design criterion is unsafe

New design charts developed

Caution is needed for extrapolation

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Questions?