Surface Wave Method: A Tool for Lifeline Earthquake Engienering.
Surface Wave Method: A Tool for Lifeline Earthquake
Andrus, R. D.
Earthquake Engineering Site Characterization. Research
Needs Workshop Proceedings. Miscellaneous Paper
GK-97-21. Appendix G. U.S. Army Corps of Engineers.
Final Report. September 1997, U.S. Army Corps of
Engineers, Vicksburg, MS, Koester, J. P.; Holmes, T. L.,
Editor(s)(s), G1-G14 pp, 1997.
earthquakes; geophysical methods; in situ measurement;
lifelines; SASW testing; soil liquefaction; shear wave
Liquefaction of granular soils is one of the major
causes of lifeline damage in past earthquakes.
Screening techniques based on geology, hydrology, and
soil conditions can identify areas along the lifeline
corridor requiring more rigorous analyses. These areas
can extend for several kilometers, however. The
Spectral-Analysis-of-Surface-Waves (SASW) method has
great potential for rapid determination of the layer
thickness and small-strain shear wave velocity, Vs, of
soil deposits. The SASW method is nonintrusive and
nondestructive. It is based on the principal that
surface seismic waves of high frequency propagate only
in near-surface layers, and surface waves of low
frequency propagate at different velocities if stiffness
varies with depth. Thus, different portions of the soil
profile can be tested by using surface waves over a wide
range of frequencies. The general SASW test
configuration of source, receivers, and recording
equipment is shown in Figure 1. Liquefaction potential
and Vs, of granular soils are influenced by many of the
same factors (e.g., density, confinement, and geologic
age). This paper evaluates the ability of the SASW
method to delineate liquefiable soil using data from two
sites (Goddard Ranch and Larter Ranch) where
liquefaction occurred during the 1983 Borah Peak, Idaho,
earthquake and the liquefaction assessment procedure by
Stokoe et al. Application of the SASW method to
lifelines is discussed.