On the volumetric deformation of reconstituted soils

This paper reviews the phenomenon of volumetric hardening, which is a commo n feature of the mechanical behaviour of many gee-materials. Three differen t material idealizations have been proposed to describe this hardening, and the paper contains the corresponding mathematical formulation. These ideal izations vary in their complexity and hence their ability to capture differ ent aspects of real material behaviour. Any of the three postulates can be implemented into most constitutive models. As a demonstration of their capa bilities, the postulates have been implemented into the well-known modified Cam Clay model, and computations are made with the resulting new constitut ive models. It is seen that the new models can successfully represent impor tant features of soil behaviour such as plastic yielding associated with lo ading inside the current virgin yield surface, the loosening or densifying of granular soils caused by shearing, and the accumulation of both volumetr ic and distortional deformation caused by repeated drained loading over a l arge number of cycles. Copyright (C) 2000 John Wiley & Sons, Ltd.