Strain-rate change effects in reconstituted London clay using a viscoplastic subloading model

Abstract

This paper illustrates the capability of a viscoplastic subloading model recently proposed in reproducing strain-rate change effects in soil. The viscoplastic model used is based on the subloading surface concept making possible the occurrence of viscoplastic strains inside the yield surface. After a brief description of the basic principles and constitutive relations behind the model, a numerical simulation of an undrained triaxial compression test on a normally consolidated reconstituted London clay with several strain-rate changes was performed with success. This result was obtained with a general soil model which did not take into account these specific temporary effects in its formulation. The influence of the strain–acceleration during the strain-rate transitions on the model’s response was also analysed. The temporary effects were found to be influenced by the value of the strain–acceleration. However, for the values normally used in the laboratory tests, the temporary effects seem to be insensitive to it.