Numerical assessment of effects of strain rate on the critical state of crushable sand

This study highlights the effects of strain rate on the critical state (CS) response of crushable sand. A set of drained triaxial tests is simulated using the discrete element method (DEM) to understand the rate effects on the stress–strain and volumetric behaviour of the granular sample. The DEM parameters are obtained by comparing the stress–strain and particle crushing behaviour of in-house experimental analysis on crushable coral sand under a slow strain rate. In DEM, the particles are subjected to varied strain rates under different initial confining pressures and initial densities to capture the rate effects on macroscopic responses until the CS. It is observed that crushing increases with an increase in confining stress. However, a higher strain rate induces relatively lower crushing and higher strength in terms of both peak stress and residual stress. It is observed that in pressure–volume space, the CS line alters with the increasing strain rate of the crushable samples, especially under high-confining conditions, whereas the effect of strain rate on CS seems to be negligible under low-confining conditions due to the absence of particle crushing.