Title: The Use of MASW in the Assessment of Soil Liquefaction Potential
1The Use of MASW in the Assessment of Soil
Liquefaction Potential
- Chih-Ping Lin
- C-C Chang, I-L Chen, T-S Chang
- National Chiao Tung University, Taiwan
- November 4, 2003
2Outline
- Backgrounds
- Multi-channel Analysis of Surface Wave
- Verification Case
- 2-D Imaging of Liquefaction Potential
- Summary
3Acknowledgement
- Funding for this research was provided by the
National Science Council and Institute of
Planning Hydraulic Research.
4Field Tests for assessing liquefaction potential
- 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
response
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2
3
4
5
5Shear Wave Velocity Measurements
- Cross-hole
- Down hole
- Seismic cone
- Suspension PS-logger
- Surface wave method
- Non-invasive
- Efficient
- Cost effective
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2
3
4
5
6Basic Principle of Surface Wave Method
1
Frequency component
Geophones
2
VS
VS1
3
4
VS2
5
VS3
z
Dispersion curve
Field Testing
V
Dispersion analysis
Inversion
f
7Surface 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)
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2
3
4
5
8SASW Method
1
Df
2
3
4
5
Unwrapping in f domain
Df
v
f
f
9Multi-station Data Acquisition
1
u(tm,xn)
Measurement
f 10, v 200 m/s
2
3
4
5
t
t-x domain
x
10MSASW Method
1
DFT w.r.t. time domain
2
3
4
5
f
f
R2
x
11MWTSW Method
k
1
DSFT w.r.t. space domain
2
3
t-x domain
4
5
f-x domain
f-k domain
f-v domain
12Multi-station Analysis of Surface Wave
1
0
1
N-2
N-1
2
x0
Dx
L
3
Source
4
Geophone
5
13Multi-station Wavefield Transform
1
2
3
4
f-k
f-p
5
f-l
f-v
14Verification Case - Site
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2
3
4
5
15Seismic Equipment
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2
3
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5
16Verification Case Field Testing
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2
3
4
5
17Verification Case Dispersion AnalysisDx 0.5
m, L 11.5 m
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2
3
4
5
18Verification Case Dispersion AnalysisDx 1 m,
L 23 m
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2
3
4
5
19Verification Case Dispersion AnalysisDx 1 m,
L 23 m
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2
3
4
5
20Verification Case Inverse Analysis
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2
3
4
5
21Verification CaseVs and FS against liquefaction
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2
3
4
5
22Surface Wave Seismic Imaging
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2
3
4
5
23Surface Wave Seismic Imaging
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2
3
4
5
24Surface Wave Seismic Imaging
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2
3
4
5
25Andrus and Stokoe (2000)
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26Summary
- Advantages of MASW
- Field testing simple efficient
- Multi-station redundancy
- Automation site quality control
- Robustness dispersion curve visualized
- 2-D imaging
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2
3
4
5
27Summary
- 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
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2
3
4
5
28Thank You!
- Chih-Ping Lin
- Geotechnical Engineering Group
- National Chiao Tung University