| S-wave velocities and the rigidity moduli derived from them are the major geophysical parameters of the near surface ground. For instance, averaged S-wave velocity for the near surface down to 30 m (AVS30) is needful to assess the site condition for seismic design. Suspension PS-loggings conducted in drill holes and direct pushing seismic CPT have been adopted to obtain 1-D reliable S-wave velocity profile for years. Furthermore, multichannel analysis of surface waves (MASW, e.g. Park et al., 1999) has been broadly employed for reconstructing 2-D S-wave velocity structure in the near surface. On the other hand, dynamic testing methods including triaxial resonant column testing were the most common laboratory methods for estimating S-wave velocity of unconsolidated specimen under small strain condition. It is also possible to evaluate nonlinear property of a soil specimen from stress-strain curves. However, the conventional laboratory testing method requires high quality and undisturbed samples as well as high precision and wide dynamic ranging apparatus. Consequently it resulted in a large expense. |
