Dynamic signatures of cavities and buried objects obtained from surface wave testing

Application of surface waves in detection and characterization of underground cavities and buried objects is presented. Waves reflected from cavities and buried objects in the ground, contain information that can be described as a dynamic signature of an object. Properly interpreted, the analyzed reflections can lead to discrimination between cavities and objects denser than the surrounding soil, and to estimation of their size. Seismic test is simulated using finite element analysis. Signal recorded at several surface locations, in relative proximity of the sought object, is analyzed using continuous wavelet transforms. Results of a parametric study are presented, with an objective to demonstrate influence of some of the parameters and to determine limitations of the proposed approach. The parameters analyzed include: the shear wave of the object, shape of the object, size of the object relative to the depth of embedment, and position of the receivers relative to the object.