Low-strain shear modulus dependence on water content of a natural stiff clay

Abstract

This paper shows the results of an experimental programme aimed at evaluating the low-strain shear modulus of a stiff clay (Boom clay, Belgium) and its dependency on water content changes (or, alternatively, degree of saturation or suction) and hydraulic history. Resonant column and bender element tests were carried out at different hydraulic states. Drying and wetting paths were followed using vapour equilibrium technique, in which samples were allowed to equalise in sealed chambers at controlled relative humidity (44% to 97%). Time domain technique has been used to determine the travel time in bender element tests. The evolution of the shear modulus was carefully monitored along these hydraulic paths. Shear moduli results and their dependence on water content (suction or degree of saturation) and stress/hydraulic history, are discussed and interpreted. In addition, discrepancies observed in the results between the two dynamic techniques are evaluated and discussed.