Cavity expansion analyses of crushable granular materials with state-dependent dilatancy

Crushability is one of the important behaviors of granular materials particularly under high stress states, and affects both the deformability and strength of the materials that are in essence associated with state-dependent dilatancy. In this presentation, first, a new critical state model is proposed to take into account the three different modes of compressive deformation of crushable granular materials, i.e. particle rearrangement, particle crushing and pseudo-elastic deformation. Second, the governing equations for cavity expansion in crushable granulates are introduced, in which the state-dependent dilatancy as well as the bounding surface plasticity model are used. Then, the procedure to obtain semi-analytical solutions to cavity expansion in the material is described in detail, in which a commercial differential equation solver is employed. Finally, cavity expansion analyses are carried out on Toyoura sand, a well-documented granular material, to demonstrate the effects of crushability and state-dependent dilatancy. The study shows that particle crushing does occur at both high stress and critical states and affects the stress fields and the deformation behavior of the material surrounding the cavity in association with state-dependent dilatancy. This leads to conclusion that particle crushing and state-dependent dilatancy have to be taken into account when cavity expansion theory is used to interpret cone penetration tests and pressuremeter tests. Copyright (c) 2011 John Wiley & Sons, Ltd.