Surface-wave Dispersion Inversion versus SH-wave Refraction Tomography in Saturated and Poorly Dispersive Quick Clays

A seismic survey involving two distinct acquisition setups, with vertical and horizontal component geophones, has been carried out along the same line on a site presenting a simple vertical structure (peat, quick clays and bedrock) and no strong lateral variations. SH-wave refraction tomography and Rayleigh-wave dispersion inversion provided the same shear-wave velocity gradient in the quick clays. SH-wave tomography failed to correctly depict the peat layer and to reach the bedrock. A collection of Rayleigh-wave dispersion images were extracted along the line using windowing and stacking techniques. A thorough analysis of these images made it possible to give a complete description of the site velocity structure, illustrating the complementarity of both methods.