the use of masw in the assessment of soil liquefaction potential chih-ping lin c-c chang, i-l chen,...
TRANSCRIPT
The Use of MASW in the Assessment of Soil Liquefaction
Potential
Chih-Ping LinC-C Chang, I-L Chen, T-S Chang
National Chiao Tung University, TaiwanNovember 4, 2003
Outline
1. Backgrounds
2. Multi-channel Analysis of Surface Wave
3. Verification Case
4. 2-D Imaging of Liquefaction Potential
5. Summary
Acknowledgement Funding for this research was provided by the
National Science Council and Institute of Planning & Hydraulic Research.
Field Tests for assessing liquefaction potential
1
2
3
4
5
Standard Penetration test（ SPT） Cone Penetration Test（ CPT） Shear Wave Velocity Measurements (SWV)
Vs vs. Liquefaction resistance Effects of large particles minor Non-invasive method can be used Can be measured in the lab and in-situ Directly related to Gmax required for site respon
se
Shear Wave Velocity Measurements
1
2
3
4
5
Cross-hole Down hole Seismic cone Suspension PS-logger Surface wave method
Non-invasive Efficient Cost effective
Basic Principle of Surface Wave Method
1
2
3
4
5
VS1
VS2
VS3
VS
z0 10 20
0
0.05
0.1
0.15
0.2
Tim
e (
s)
Frequency component Geophones
f
VDispersion curve
Inversion Dispersionanalysis
Field Testing
Surface Wave Methods Two-station methods
Steady-state Rayleigh wave method (SSRW) Spectral analysis of surface wave (SASW)
Multi-station Method Phase-offset regression (MSASW) Multi-station wavefield transformation of
surface wave (MWTSW)
1
2
3
4
5
SASW Method
xff
fv
)(
2)(
Unwrappingin f domain
f
f
v
1
2
3
4
5
Multi-station Data Acquisition
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
Distance (m)
Tim
e (
ms)
0 20 40 60 80 100
0
50
100
150
200
250
300
350
400
450
500
k
T = 2/
1
v
fv t-x domain
1
2
3
4
5
u(tm,xn) Measurement: f =10, v = 200 m/s
x
t
MSASW Method
50
100
150
200
250
Distance (m)
Fre
que
ncy
(Hz)
0 10 20 30 40 50
0
10
20
30
400 10 20 30 40 50
-15
-13
-11
-9
-7
-5
-3
-1
1
3
5
Pha
se A
ngle
(ra
d)
f-x domain
2
xUnwrappingin x domain
1
0
2exp),(1
),(M
mminmni tfjxtu
MxfU
xff
fv
)(
2)(
DFT w.r.t.time domain
1
2
3
4
5
x
f R2
MWTSW Method
0.5
1
1.5
2
2.5
3x 10
4
Phase Velocity, vph (m/s)
Fre
que
ncy,
f (H
z)
200 400 600 800 1000
5
10
15
20
25
30
f-k domain
f-v domain
f-x domain
t-x domain
1
0
2exp),(),(
N
nn
inii x
v
fjxfUvf
DSFT w.r.t.space domain
k1
2
3
4
5
Multi-station Analysis of Surface Wave
1
2
3
4
5
： Source
：Geophone
L
x0 x
0 1 N-2 N-1
Multi-station Wavefield Transform
1
2
3
4
5
500
1000
1500
Wavenumber, k
Fre
qu
en
cy, f (H
z)
2 4 6 8 10 12
20
40
60
80
500
1000
1500
Slowness, p (s/m)
Fre
qu
en
cy, f (H
z)
2 4 6 8
x 10-3
20
40
60
80
500
1000
1500
Velocity, v (m/s)
Fre
qu
en
cy, f (H
z)
200 400 600
20
40
60
80
500
1000
1500
Wavelength (m)
Fre
qu
en
cy, f (H
z)
20 40 60
20
40
60
80
f- f-v
f-k f-p
Verification Case - Site
1
2
3
4
5
Seismic Equipment
1
2
3
4
5
Verification Case – Field Testing
1
2
3
4
5
Verification Case – Dispersion Analysis
Dx = 0.5 m, L = 11.5 m
1
2
3
4
5
15 20 25
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Tim
e (
s)
Offset (m)15 20 25
0
10
20
30
40
50
60
70
80
90
100
freq
uen
cy (
Hz)
Offset (m)0 0.5 1
0
10
20
30
40
50
60
70
80
90
100
R2
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
Phase Velocity, vph
(m/s)0 500
0
10
20
30
40
50
60
70
80
90
100
MWTSWMSASW
Verification Case – Dispersion Analysis
Dx = 1 m, L = 23 m
1
2
3
4
5
20 30 40
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Tim
e (s
)
Offset (m)20 30 40
0
10
20
30
40
50
60
70
80
90
100
freq
uen
cy (
Hz)
Offset (m)0 0.5 1
0
10
20
30
40
50
60
70
80
90
100
R2
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
Phase Velocity, vph
(m/s)0 500
0
10
20
30
40
50
60
70
80
90
100
MWTSWMSASW
Verification Case – Dispersion Analysis
Dx = 1 m, L = 23 m
1
2
3
4
5
20 30 40
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Tim
e (
s)
Offset (m)20 30 40
0
10
20
30
40
50
60
70
80
90
100
freq
uenc
y (H
z)
Offset (m)
0 0.5 1
0
10
20
30
40
50
60
70
80
90
100
R2
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
Wavelength (m)0 20 40
0
10
20
30
40
50
60
70
80
90
100
MWTSWMSASW
Verification Case – Inverse Analysis
1
2
3
4
5
0 5 10 15 20 25 30 350
50
100
150
200
250
Phase Velocity, vph
(m/s)
Fre
qu
en
cy, f
(H
z)
Measured Predicted
Verification CaseVs and FS against liquefaction
0 100 200 300 4000
5
10
15
20
25
shear wave velocity (m/s)
de
pth
(m
)
CPT 1CPT 2CPT 3MASW 3
4
5
1
20 1 2 3
0
5
10
15
20
25
FS
de
pth
(m
)
CPT 1CPT 2CPT 3MASW
Surface Wave Seismic Imaging
3
4
5
1
2
Surface Wave Seismic Imaging
200
300
400
500
50 100 150 200 250 300
0
10
20
30
Distance, x (m)
De
pth
, z (
m)
3
4
5
1
2
0.5
1
1.5
2
50 100 150 200 250 300
0
10
20
30
Distance, x (m)
De
pth
, z (
m)
Surface Wave Seismic Imaging
0.5
1
1.5
2
0 50 100 150 200
0
5
10
15
20
Distance, x (m)
Dep
th, z
(m
)
0.5
1
1.5
2
0 50 100 150 200 250
0
5
10
15
20
25
Distance, x (m)
Dep
th, z
(m
)
0.5
1
1.5
2
0 50 100 150 200 250 300 350
0
5
10
15
20
25
30
Distance, x (m)
Dep
th, z (
m)
3
4
5
1
2
1.6
1.8
2
0 50 100 150 200 250 300 350
0
10
20
30
Distance, x (m)
Dep
th, z
(m
)
1.4
1.6
1.8
2
0 20 40 60 80 100 120 140
0
10
20
30
Distance, x (m)
Dep
th, z
(m
)
0.5
1
1.5
2
0 50 100 150
0
10
20
30
40
Distance, x (m)
Dep
th, z
(m
)
0.5
1
1.5
2
0 50 100 150 200 250
0
10
20
30
Distance, x (m)D
epth
, z (m
)
0.5
1
1.5
2
0 50 100 150 200 250 300 350
0
10
20
30
Distance, x (m)
Dep
th, z
(m
)
Andrus and Stokoe (2000)1
2
3
4
5
Summary
3
4
5
1
2
Advantages of MASW Field testing simple & efficient Multi-station redundancy Automation: site quality control Robustness: dispersion curve visualized 2-D imaging
Summary
3
4
5
1
2
The results show that the MASW efficient, cost effective, and non-invasive useful in gravelly soils effective for ‘first look’ or investigation of
lateral variations
Further Research Lateral resolution Inversion and vertical resolution
Thank You!
Chih-Ping Lin
Geotechnical Engineering Group
National Chiao Tung University