Relationship between Shear-Wave Velocity and Geotechnical Parameters for Norwegian Clays

Abstract

A database of shear-wave velocity (Vs) measurements using a variety of techniques and soil properties measured on high-quality samples for 28 Norwegian sites has been established. The purpose was to evaluate the different methods of measuring Vs, to present guidelines and correlations to assist in estimating Vs profiles in these clays in the absence of site-specific data, and to outline relationships that can be used to give first-order estimates of soil properties. It was found that consistent measurements of Vs can be obtained from a variety of techniques and that for practical engineering purposes the Vs values obtained from the different methods are similar. Surface wave techniques can be particularly useful but careful survey design is necessary and in particular the inversion process needs to be carefully controlled. Differences of about 15–20% can be obtained in the Vs values depending on the algorithm used. Vs values for Norwegian clays are consistent with well-established frameworks for other materials, based on relationships between effective stress and index parameters. Piezocone penetration testing (CPTU) can be used to give acceptable estimates of Vs and this includes techniques which utilize the CPTU data only and are independent of any index property. Vs correlates well with triaxial compression and direct simple shear derived undrained shear strength (su) values. There appears to be a particularly good link between Vs and preconsolidation stress (pc′). Satisfactory relationships also exist between Vs and the tangent moduli of the clays at in situ stress (M0) and at pc′ (ML).