The spectral analysis of surface waves (SASW) test is a seismic method for determining the shear wave velocity (Vs) profile of a site. Three components need to perform the SASW test: field test for data collection, evaluation of experimental dispersive curve by phase unwrapping method, and determining the Vs profile of a site by inversion process. Previous studies have shown that errors may arise in experimental dispersive curve when conventional SASW test and data analysis procedures are followed. In this study, the wavelet transform is introduced to evaluate the experimental dispersive curve without using phase unwrapping method. The wavelet-based SASW method was performed at four sites, and the Vs profiles determined by the proposed method are compared with the results of PS logging tests. The determined Vs profile by the proposed method is close to the results of PS logging test for the depth less than 25 m.
The shear wave velocity (V s) profile is an important geotechnical parameter for the evaluation of dynamic soil behavior and static deformation of the ground (Taniguchi and Sawada, 1979; Woods and Jedele, 1985; Burland et al., 1977). Many field seismic tests such as crosshole, downhole, suspension PS logging, spectral analysis of the surface wave (SASW), and multi-channel analysis of the surface wave (MASW) are now available to evaluate the V s profiles of a site (Bang and Kim, 2007). Generally, borehole seismic methods provide better results whereas surface wave methods are more efficient and economics. Since the surface wave methods apply an inverse process without using the shear wave directly, there are somewhat uncertain for the determined V s profiles. The phase unwrapping method is the most common method to evaluate the experimental dispersive curve of a site. Previous studies have shown the defects of the phase unwrapping method (Al-Hunaidi, 1992; Al-Hunaidi, 1993) and researchers have also proposed some other methods to evaluate the experimental dispersive curve (Al- Hunaidi, 1994, Kim and Park, 2002).
