2012 IEEE Colloquium on Humanities, Science & Engineering Research (CHUSER 2012), December 3-4, 2012, Kota Kinabalu,
Sabah, Malaysia
Site-Specific Empirical Correlation between Shear
Wave Velocity and Standard Penetration Resistance
using MASW Method
Chee-Ghuan Tan
School of Civil
Engineering, Universiti
Sains Malaysia,
Penang, Malaysia
[email protected]
Taksiah A. Majid
Kamar Shah Ariffin
Disaster Research Nexus,
School of Civil
Engineering, Universiti
Sains Malaysia,
Penang, Malaysia
School of Material and
Mineral Resources,
Universiti Sains
Malaysia,
Penang,Malaysia
II.
SURFACE WAVE METHOD
Surface wave geophysical methods have been developed
few decades ago and lots of application in geotechnical
engineering. Surface wave geophysical methods able to
determine dynamic properties of soil, particularly the shear
wave velocity profile as well as the shear modulus. These
properties are main parameters in estimating the soil response
and soil-structure interaction to seismic loading [6]. Surface
wave methods offer advantages over other surface based in-situ
seismic techniques is rapid, cost effective, noninvasive and
ability to detect low velocity layer underneath higher velocity
layer of deposit provides more accurate site characterization.
Keywords- Shear wave velocity profile, Multichannel analysis
of surface wave (MASW), Standard penetration resistance,
Empirical correlation
A. Multichannel Analysis of Surface Waves (MASW)
Spectral analysis of surface wave (SASW) method was
introduced by Stokoe and Nazarian [7] which focuses on
analyzing the ground roll dispersion relation to produce nearsurface S-wave velocity profile. The main drawbacks are time
consuming and inherent difficulties when evaluating and
distinguishing signal from noise with only a pair of receivers.
To overcome the few drawbacks of the SASW method, a new
technique Multichannel Analysis of Surface Waves (MASW)
was developed by four-phase research project team from
Kansas Geological Survey. Multi-station recording permits a
single survey of a broad depth range and higher levels of
redundancy with a single field configuration compared with
SASW [8]. A multichannel shot gather decomposed into a
swept frequency record allows the fast generation of an
accurate dispersion curve. This dispersion curve is then used to
determine the shear-wave velocity profile for the shallow-depth
layer of soil [9].
INTRODUCTION
The most important aspect in earthquake engineering is to
determine the dynamic soil properties. The dynamics soil
properties able to provide the important information of the
dynamic response of the soil-structure which needed in
dynamic structural analysis of the superstructures. The local
soil structure also play a major role in the seismic soil
amplification of a site which is a critical factor affecting the
level of ground shaking [1]. However, lacking of
understanding the geological information of the site often
responsible for structure and environmental failure occurred.
The soil stiffness and soil amplification factor on ground
surface are always presented by Vs30.
Field measurement of shear wave velocity includes
cross-hole test, downhole test, suspension logging, seismic
This study was supported by the Postgraduate Research Grant Scheme
given by Universiti Sains Malaysia.
978-1-4673-4617-7/12/$31.00 ©2012 IEEE
School of Civil
Engineering, Universiti
Sains Malaysia,
Penang, Malaysia
Malaysia
reflection, seismic refraction and surface wave. However,
surface wave test is simpler and efficient technique compared
to other in-situ test in measuring the shear wave velocity. It is
not economically feasible to conduct test at all sites. Therefore,
a reliable empirical correlation between shear wave velocity
and standard penetration resistance (Nspt) would be useful since
the ease of obtaining the Nspt from site investigation report.
Several researchers have proposed empirical correlation for
shear wave velocity based on standard penetration test [2-5].
However, these empirical correlations are region specific and
cannot be applicable to all regions.
Abstract—In seismic engineering, dynamic property of the soil is
one of the most important aspects in ground response analysis. It
is significantly affected by the presence soil deposits of the site.
Generally, the average shear wave velocity at top 30 m (Vs30) of
soil deposit is used to represent stiffness of the soil and is one of
the important parameters to determine the soil amplification
factor on the ground surface and site classification. Vs30 is usually
determined by carry out wave propagation test on the field.
However, it is not economically feasible to conduct test at all sites.
Therefore, a reliable empirical correlation between shear wave
velocity and standard penetration resistance (Nspt) would be
useful since the ease of obtaining the Nspt from site investigation
report. Although there are quite a number of these empirical
correlations available in literature, but they are region specific
and cannot be applicable to all region. In this study,
Multichannel Analysis of Surface Wave (MASW) is employed to
obtain the shear wave velocity profile of site which needed to
develop the empirical regression equations between Vs and Nspt
for sand, silt and clay. MASW test has been carried out on the
twenty sites which posses of Nspt profiles around Penang Island.
The empirical regression equations developed by the study area
are exhibit good prediction performance. It can be used for the
area which consist of soft to stiff clay and silt and loose to dense
sand.
I.
Norazura Mohamad
Bunnori
94
2012 IEEE Colloquium on Humanities, Science & Engineering Research (CHUSER 2012), December 3-4, 2012, Kota Kinabalu,
Sabah, Malaysia
B. Field Test Set up and Procedure
Extensive MASW tests were carried out
o in the Penang
Island as shown in Fig. 1. GEOMETR
RICS-24 channels
seismograph (Geode) with single geode operating
o
software
(SGOS) is used for the MASW tests. 244 units of vertical
geophones with natural frequency of 4.5 Hz were used to
receive the wave signal generated by an actiive source of 8 kg
sledgehammer vertically hit on a striker platee. Geophones were
deployed linearly with equal spacing in the range
r
of 0.5 to 2 m
interval as suggested by Maheswari et al.. [1]. The nearest
source to geophone offsets are in the range off 5 to 15 m to meet
the requirement of different type of soil harddness suggested by
Xu et al. [10]. The planer characteristic of surface waves
evolve only after some distant from the soource and hence it
normally need to be greater than half of the maximum desired
SW is illustrated in
wavelength. The field configuration of MAS
Fig. 2. The acquired wave data from the field
f
measurement
were analysis using SeisImager softwaare and can be
summarized to two main steps: (i) develoop the dispersion
curves of Rayleigh wave phase velocity and (ii) inversion of
dispersion curve to obtain the shear wave veelocity profiles. At
first, the raw wiggle plot obtained from the
t field test was
filtered to reduce the random noise effect andd interference with
other waves as shown in Fig. 3(a). After filttered, only surface
wave is used in generating the dispersion cuurve analysis. The
amplitude of body wave and higher mode of Rayleigh wave
a high frequencies
may dominate over the fundamental mode at
range if the raw data is not well filtered. Only fundamental
mode of Rayleigh wave is picked from the frequencies of 5-8
to 40-50 Hz as shown in Fig. 3(b) to generatte dispersion curve
with signal to noise ratio (S/N) (Fig. 3(c))). The dispersion
curve was inverted to estimate the shear wavve velocity profile
as shown in Fig. 4. Fig. 5 shows the tyypical shear wave
velocity profile and Nspt.
Sledgehammer
with trigger
switch
Geo
ophones
(4.5
5 Hz)
Multichannel
Seismograph (GEODE)
Laptop
Vs1
Vs2
Vs3
Figure 2. Field configuuration of MASW method
Time (ms)
Disttance (m)
(
(a)
Frequency (Hz)
Phase velocity
v
(m/s)
(
(b)
Phase velocity (m/s)
Frequuency (Hz)
(
(c)
Figure 3. Development of the disperrsion curves: (a) typical raw wiggle plot
obtained from the field test (b) picking of maximum wave signal (c) dispersion
curve with quality curvve (signal to noise ratio)
Figure 1. Location of geophysical invesstigation
95
2012 IEEE Colloquium on Humanities, Science & Engineering Research (CHUSER 2012), December 3-4, 2012, Kota Kinabalu,
Sabah, Malaysia
Depth (m)
S-velocity (m/s)
Figure 6. Correlation between Vs and Nspt for sand, silt and clay
Figure 4. Typical shear wave velocity profile obtainned from MASW test
III.
The shear wave velocity obtained
o
from Equation 1-3 for
sand, silt and clay are coompared with some selected
correlations proposed by earlieer researcher which have closest
correlation curve with the prroposed equation (Table 1) as
shown in Fig. 7. However, the correlation for clay gives
slightly higher shear wave velocity
v
compared to existing
correlation. Some discrepanccy between the proposed and
previous correlations may duee to different site geotechnical
conditions and the proceduress during carry out the MASW
survey in site.
DEVELOPMENT OF EMPIRICAL CORREELATIONS FOR VS
AND NSPT
In-situ test to determine the shear wave velocity profile is
f
to conduct
always preferable but it is not economically feasible
test at all sites. A reliable empirical correlatioon between Vs and
Nspt would be in advantage. In this study, Vs and Nspt data were
collected from twenty sites in the generatioon of its empirical
correlations. Simple regression analysis was used to develop
these correlations. The new empirical correelations with their
correlation coefficient (R2) for sand, silt and clay are proposed
as follows:
Vs = 150.00 Nspt 0.2292 (R2 = 0.6874), Sand
(1)
Vs = 111.62 Nspt 0.3233(R² = 0.7175), Silt
(2)
Vs = 118.33 Nspt 0.3276 (R² = 0.7142), Clay
(3)
IV.
O
CONCLUSION
In summary, an extensive meassurement of shear wave velocity
by employing MASW geophysical technique was carried out in
Penang Island. The correlationns between Vs and Nspt for sand,
silt and clay were developed. The
T results proved the previous
finding that Nspt is the main parrameter to determine shear wave
velocity. Generally the shear wave velocity curves proposed
are closely lying to the existting correlation. Therefore, the
proposed correlations for sand,, silt and clay are recommended
to be used in the studied area.
Fig. 6 shows the Vs-Nspt raw data annd the regression
correlations for sand, silt and clay. The results
r
proved the
previous finding that Nspt is main parameter while
w
soil material
gives less significant effect on shear wave vellocity estimation.
TABLE I.
No.
Authors (year)
1
Okamato et al.
(1989)
Lee (1990)
2
3
4
Figure 5. Typical shear wave velocity profile and Nspt variation for site
96
Hanumantharao
and Ramana
(2008)
Maheswari and
Boominathan
(2009)
CORRELATIONS BETWEEN VS AND NSPT
Vs Correlation
Sand
Vs = 125 N 0.33
Vs = 79 N 0.43
Silt
Clay
Vs = 105.6 N 0.32
Vs = 114.4 N 0.31
Vs = 86.0 N 0.42
Vs = 89.3 N0.36
2012 IEEE Colloquium on Humanities, Science & Engineering Research (CHUSER 2012), December 3-4, 2012, Kota Kinabalu,
Sabah, Malaysia
RENCES
REFER
[1]
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(a)
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(b)
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[9]
(c)
Figure 7. Comparison between proposed and existing correlations for Vs and
Nspt for: (a) sand (b) silt (c) clay
[10]
ACKNOWLEDGEMENTS:
This study was supported by the Postgraduaate Research Grant
Scheme given by Universiti Sains Malaysia. The
T authors would
like to extend their gratitude to the Ministrry of Education of
Malaysia for permission to collect data from
m both primary and
secondary schools.
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