AUTOMATED SURFACE-WAVE METHOD - INVERSION TECHNIQUE

The spectral-analysis-of-surface-waves (SASW) method is a nondestructi ve testing, method based upon generation and detection of elastic stre ss waves. The key steps involved are construction of an experimental d ispersion curve froin data collected in situ, and inversion of the dis persion curve to determine the stiffness profile. An automated algorit hm for determining the representative dispersion curve from field data has been presented in a companion paper. In most applications, the de termination of the layer moduli are accomplished by using a manual tri al and error process (forward modeling). Unfortunately, this process i s rather time-consuming and requires engineering judgement. To improve this aspect of SASW testing, an automated technique based upon the ge neral inverse theory is described here. The technique provides a fast procedure for simultaneously determining shear wave velocity and thick ness of different layers. In addition, some description of uncertainty in the determined results is provided.