Effect of Temperature and Water Content on Creep...
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1 Effect of Temperature and Water Content on Creep behavior of Grouted Anchors Chuang Lin, Liangbiao Chen and Xiong Zhang University of Alaska Fairbanks
Transcript of Effect of Temperature and Water Content on Creep...
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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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Basis Creep Behavior
I:Primary
Dis
plac
emen
t, u
Time, t
II:Secondary
III:Tertiary
P
u
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Vyalov, 1966; Biggar and Kong, 2001
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Creep Equation
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)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 .
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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 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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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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