Influence of sample conditions on shear wave velocity measurements in a sedimentary stiff clay

Abstract

The study presented in this paper aims to investigate the prospects of using bender elements in the offshore industry for determining shear wave velocity of fragmented, fragile and brittle clay samples and cuttings. The result from the study shows that the laboratory-measured S-wave velocities of intact samples of Søvind Marl, a sedimentary stiff Palaeogene clay, in general, are lower than those determined from in-situ seismic cone penetration testing. The reason may be unavoidable volume-constant distortion and changes to effective stress conditions experienced by the natural clay upon sampling and subsequent sample preparation. Correlation between the size of the samples and velocity is not noticed. In contrast, the S-wave velocities for natural samples that were remoulded and then reconstructed are observed to be comparable with the in-situ seismic measurements, however, the results are found to be dependent on sample density. The influence of cross-talk, near-field, and boundary effects on the results is assessed. © 2020 Informa UK Limited