Automated Surface Wave Method: Inversion Technique

Abstract

The spectral‐analysis‐of‐surface‐waves (SASW) method is a nondestructive testing method based upon generation and detection of elastic stress waves. The key steps involved are construction of an experimental dispersion curve from data collected in situ, and inversion of the dispersion curve to determine the stiffness profile. An automated algorithm for determining the representative dispersion curve from field data has been presented in a companion paper. In most applications, the determination of the layer moduli are accomplished by using a manual trial and error process (forward modeling). Unfortunately, this process is rather time‐consuming and requires engineering judgement. To improve this aspect of SASW testing, an automated technique based upon the general inverse theory is described here. The technique provides a fast procedure for simultaneously determining shear wave velocity and thickness of different layers. In addition, some description of uncertainty in the determined results is provided.