On the elasticity and plasticity of dilatant granular materials

We present a model which simulates the response of a granular material (made up of nonplastic grains) to small cyclic shear strain. The model is based upon a dissipation function representing energy dissipated as plastic deformation and a quadratic dilatancy rule describing the volume response which produces kinematic hardening. Elastic deformation is included in the model through a function describing the rate at which it is stored as deformation occurs. Two sets of experimental data (one for a shear test, the other for a circular loading test) are used to evaluate the accuracy of the model. For the shear test, both the shear strain-shear stress curve and the shear strain-volume strain curve are reproduced well. In the circular loading test, the principal strain response and volume response are modelled realistically. (C) 1999 Elsevier Science Ltd. All rights reserved.