Detection of underground obstacles by SASW method - Numerical aspects

The ability of the spectral analysis of surface waves (SASW) test to detect underground obstacles has been investigated. The SASW test is simulated by the finite-element method. The fluctuations in the dispersion curve, due to Rayleigh waves reflected from an obstacle, are used to detect the obstacle. Both rigid obstacles and cavities with a variety of shapes and embedment depths are considered. Obstacles in a homogeneous half-space, a layered half-space, and a pavement profile are detected. Finite-element results are compared to the available experimental results and verified by a simple mathematical model. The results indicate that the SASW test can detect an underground obstacle effectively, provided that the obstacle is relatively close to the surface. A scheme to use the surface waves for obstacle detection (SWOD) has been proposed.