U.S.-Taiwan Liquefaction Workshop
國立中興大學
A Study on Liquefaction Evaluation
Using Shear Wave Velocity for
Gravelly Sand Deposits
Ping-Sien Lin , National Chung-Hsing University
Fu-Sheng Chen , China Engineering Consultants, Inc.
Yin-Yu Jan , China Engineering Consultants, Inc.
Chi-Wen Chang , National Chung-Hsing University
Wen-Jong Chang , National Chi Nan University
國立中興大學
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Outline
Introduction
Literature Review
Testing Program
Results and Discussions
Conclusions
Future Works
國立中興大學
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Research Initiation
Soil liquefactions occurred in central Taiwan area
after Chi-Chi Earthquake (Mw=7.6).
Liquefactions of gravelly soil observed in the
Wufeng and Nantou Area
No proven methods for estimating the CRR of
gravelly soil because of the existence of gravels
國立中興大學
Ground settlement caused by sand boiling
(Taichung port)
國立中興大學
The Song-Gee Jewellery Store Inclined
Severely and the Footing was Suck
Research Framework
國立中興大學

In situ testing methods:
– Large Hammer Penetration Test (LPT)
– In situ shear wave velocity measurement (Vs)

Laboratory works:
– Large-scale cyclic triaxial tests (15 cm ×30 cm) to
determine CRR
– Cyclic triaxial tests with Vs measurements

Goal of research:
Find appropriate techniques for liquefaction
potential assessing in gravelly soils
國立中興大學
 Liquefaction
Literature Review
evaluation framework
– Simplified procedure proposed by Seed (1997
NCEER Workshop)
– CSR=f (M, amax, sv, rd)
– CRR from laboratory cyclic testing or in situ
tests
– FS=CRR/CSR
CRR Evaluations for Gravelly
Soils
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
BPT-Nb
– Based on correction between SPT-N and BPTNb (Harder and Seed 1986, Harder 1997)
– Need further corrections

Normalized shear wave velocity Vs1
– CRR and Vs are affected by same factors
– Nondestructive, reliable
– Procedure proposed by Andrus and Stokoe
(2000)
Correction Factors of BPT-Nb30
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
Transferred energy
N b 30
ENTHRU
 Nb
30
ENTHRU: % of the measured maximum
transferred energy with respect to the
hammer effective energy

Casing frictional force
– Computed by CAPWAP
– Effect is minimum in shallow layer
200
Rt=0
180
Rt=0.15MN
Rt=0.2MN
160
140
Rt=0.25MN
SPT-N60
120
100
80
Rt=0.47MN
60
40
20
0
-20 0
20
40
60
80
100
120
140
160
180
200
BPT-Nb30
Fig.11 Correlation of Several Casing Total
Frictional Force for BPT-Nb30 and SPT-N60
Testing Program
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 Trench
excavation
 Large hammer penetration test
 In situ shear wave velocity
measurement
 Cyclic triaxial tests with shear
wave velocity measurement
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(Fu-Tin Bridge)
Evidences of liquefaction at testing site
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(Fu-Tin Bridge)
Current Condition of Testing Site
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Current Condition of Testing Site
Table1. Soil Profile in Trench Excavation
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Δ
GWT
═
Clay layer
Percentage Finer By Weight (%)
100
90
I n s i t u Gr a i n Si z e
Di s t r i but i on Cur ve
80
70
60
Si mul a t i on Gr a i n
Si z e Di s t r i but i on
Cur ve
50
40
30
20
10
0
1000
100
10
1
0.1
0.01
Grain size (mm)
Fig. 8 Simulation Curve by Equivalent
Weight Substitution Method
0.001
Large Hammer Penetration Test
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In Situ Shear Wave Velocity Measurement
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In situ shear wave velocity near the Wufeng research
site were measured by C.P. Lin of the NCTU.
 Using the Andrus and Stokoe shear wave velocity
liquefaction assessment method showed that the
safety factor of soil layer liquefaction resistance is
less than 1.00.
(BH-1 ,amax=0.79g,Z=2.97~13.03m,FS=0.09~0.52)
(BH-2 ,amax=0.79g,Z=2.96~12.06m,FS=0.05~0.36)

Peak Horizontal
Ground
Acceleration
a max
Magnitude
Of
Earthquake
Mw
Effective
Overburden
Pressure
kg
)
s o' (
cm 2
Shear Wave Velocity
from the Research
Site
V s (m s )
Fine Content
FC(%)
Fine Content Calculation FC(%)
102.24
MSF
2.56
Mw
CSR Induced by the
Ground During the
Earthquake
a
s
CSR0.65. max. o r d
g s o'
Overburden
Pressure
Correction
0.25
p 
a

V s1V s 
s o' 
P a 100kpa
I c  1.26
FC(%)  0
1.26  I c  3.5
FC(%)  1.75 I c3.25  3.7
I c  3.5
V s1c 
FC(%)  100
Fine Content Correction
215m
FC5%
s
2150.5( FC5)m
5 FC35%
s
200m
FC35%
s
Soil Layer Liquefaction Strength
2

1
1 
V s1
CSR  a..
 b.



7.5
100
V s1c V s1 V s1c 
a 0.022;b2.8
Liquefaction Resistance Safety
Coefficient
CRR7.5
FS 
.MSF
CSR
(Andrus and Stokoe ,2000)
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Fig.14 The Profile of Shear Wave Velocity Near
the Wufeng Research Site (Lin,et al., 2002)
Large-Scale Cyclic Triaxial Test Device
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Triaxial Cell
Top plate
Accelerometer
Porous disc
Remolded
Specimen
Impact source
Bottom plate
Accelerometer
Results of the Cyclic Triaxial Tests
0.5
Cyclic Stress Ratio (CSR)
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0.4
0.3
GC=60% Dr=40%
GC＝40% Dr=40%
GC=20% Dr=40%
0.2
sample remolded by field
condition
0.1
1
By field
15
10
100
1000
Number of cycles (N l)
CSRN=15 = 0.0036 × (GC%) + 0.0050 × (Dr%) + 0.044
(R2 = 0.968)
Results of the Laboratory Vs Measurement
Vs (m/s)
Effective confining pressure (kg/cm2 )
100
200
300
0.5
1.5
2.5
3.5
4.5
5.5
400
Effective confining pressure (kg/cm2 )
Vs (m/s)
100
200
300
0.5
1.5
2.5
3.5
4.5
5.5
▓ Dr=20% GC=20%
▓ Dr=20% GC=40%
▓ Dr=20% GC=40%
▓ Dr=40% GC=40%
● Dr=20% GC=60%
● Dr=60% GC=40%
400
FS Based on Cyclic Triaxial Tests
國立中興大學

Input parameters:
– Equivalent number of cycles N1=15
(Mw=7.6)
– CSRtri,cor=0.245 (N1=15 cycles)
– amax=0.1~0.79 g
amax
0.79
0.50
0.33
0.15
0.10
CSR
0.245
0.245
0.245
0.245
0.245
CRR
0.51
0.32
0.21
0.10
0.06
FS
0.48
0.76
1.14
2.52
3.78
FS based on LPT
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BH-4
amax =0.79g
BH-2
amax =0.79g
Depth(m)
0
1
2
0
3
1
2
BH-4
amax =0.5g
BH-2
amax =0.5g
3
0
1
2
0
3
3
3
3
3
4
4
4
4
5
5
5
5
6
6
6
6
7
7
7
7
8
8
8
8
9
9
9
9
10
10
10
10
1
2
3
Table7. In Situ Shear Wave Velocities and FS
Bore Hole #1
Bore Hole #2
Depth
Vs
FS
FS
Depth
Vs
(m) (m/sec) (0.79g) (0.5g)
(m)
(m/sec)
FS
FS
(0.79g) (0.5g)
2.97
214.49
0.18
0.28
2.96
194.97
0.05
0.07
3.86
236.27
0.20
0.32
3.77
249.31
0.26
0.41
4.98
255.99
0.21
0.33
4.78
287.75
0.31
0.50
6.38
265.09
0.18
0.29
6.04
305.22
0.30
0.48
8.12
251.38
0.09
0.15
7.62
339.01
0.33
0.52
10.30
211.71
0.52
0.83
9.59
373.6
0.36
0.57
13.03
338.00
0.24
0.38
12.06
331.44
0.23
0.37
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Conclusions
1. Based on the cyclic triaxial test :
CSRfield,GC=53,Dr=31%≒ CSRtri,GC=40,Dr=40%
2. By regression method :
CSRNl=15 = 0.0036×(GC%) + 0.0050×(Dr%)+0.044
(R2 = 0.968)
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Conclusions
3. Factors of safety from LPT-Nb30 <1.0
match the field observation
LPT2, amax=0.79g,
Z=3.00~10.20m,FS=0.1~0.67
4. Factors of safety from Vs <1.0
match the field observation
BH-1 ,amax=0.79g,
Z=2.97~13.03m,FS=0.09~0.52
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Conclusions
5. With proper corrections, both LPT and
Vs methods are adequate for liquefaction
evaluation of gravelly soils
6. More research are needed in LPT
especially in evaluating the transferred
energy and casing friction
Future Works
1. Fundamental research of dynamic behavior
of gravelly soils
 Analytical framework on particulate
mechanics
 Numerical analysis to verify the contribution
in dynamic shear strain development from
gravels
2. Advanced laboratory experiments
 Measure the variation of shear wave velocity
during liquefaction process in cyclic triaxial
test
 Develop experimental technique to determine
shear wave velocity of sands in gravelly soils
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Future Works (cont.)
3. Field testing
 Establish CRR curve for gravelly soils
by in situ dynamic liquefaction test
 Explore other site characterization
techniques in liquefaction evaluation for
gravelly soils
 Evaluate the effectiveness of
remediation measures in gravelly soils
THE END