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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
2
Outline
Introduction
Literature Review
Experimental Work
Data Analysis
Conclusions
2
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
6
Creep Equation
13
)1(
n
aBu
na
n
a
n and B : soil parameters a, anchor radius
6
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
7
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)
7
We are parallel!
8
Anchor Load Tests
8
“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
9
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
9
(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
10
Literature Summary & Task 2
◦ Creep, Secondary Creep ◦ Theory & Guidelines
10
Task 1
Task 2 ◦ Anchor Load Test
◦ Ice-rich silt ◦ Grouted anchors
Load Test
11
Load Test Overview
•In laboratory •Warm temperature • ua, , and T
11
16
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
18
Pullout Failure Pattern
18
4”
1.5”
g< 2% Shear Strength not reached! Soils
2”
0.04”
19
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
19
-1.1
-1.8
damped
average
well defined
20
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%
21
Comparisons with Design Guidelines
21
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
22
Regression Model
22
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
)(
23
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
23
n
aw
maa
uT
/1
)(
SE, Standard Deviation of Error
24
Effect of Moisture Content
24
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!
25
Effect of Temperature
25
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.
27
Developed Design Guidelines
27
-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
28
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
28