Numerical-experimental Study of Seismic Surface Waves Observables on Horizontal-vertical Components for Cavity Detection

The detection of underground cavities is still a challenging problem despite the good potential of geophysical techniques. The seismic surface waves analysis method can be acceptable for the cavity localisation if observables in data are affected by the void. We propose here a combined approach based on numerical 3D simulations (Spectral Finite Element Method) and reduced-scale experimental data to assess the possible observables affected by the cavity presence. The measurement bench MUSC is designed to effectuate seismic data measurements on reduced scale models on the two component of a P-SV configuration. We highlight different observables all visible in numerical or experimental cases: 1) the diffraction event is higher on the horizontal component; 2) there is a perturbation of the direct wavefield amplitude above the cavity and after the cavity position; 3) the analyse of the elliptic particular movement is perturbed in terms of amplitude and direction above and few meters after the cavity. Test results demonstrate the capability of using different observables of the Rayleigh wavefield in presence of a cavity to detect the object. These qualitative characteristics confirm the interest to study and compare observables on the horizontal and vertical components in a medium containing a cavity.