Elastoplastic Modeling for Crushable Sands over a Large Stress Range Based on the Particle Rearranging and Crushing State

Abstract

The stress–strain behavior of granular soils is related largely to their grain-size distributions and density. If sand particles are crushed under load, some basic physical and mechanical properties of sands will be changed to a certain extent, and the traditionally defined critical state is not unique in this crushing process. To describe the complex effects of particle breakage, the volumetric and shearing responses of crushable sands to compression-shear loading are attributed to the rearranging and crushing state (RCS) of sand particles. The interrelation between rearrangement and breakage of sand particles was analyzed phenomenologically as the physical basis of this study. To characterize the RCS over a large stress range, a special curve named the RCS curve is defined in the e–ln p plane and quantified through a specific loading path. A new breakage model is proposed to correlate the crushing stress with the breakage index and to control the evolution of the RCS-curve. To account for the state-dependent dilatancy of sand particles, a new state parameter called the RCS parameter is introduced into the plastic potential function. An elastoplastic model for crushable sands was established based on the evolution of the RCS and verified by relevant triaxial test data of three representative crushable sands with an initial confining pressure ranging from 50 kPa to 68.9 MPa. The stress–strain behavior, excess pore-water pressure, and accumulated particle breakage of these crushable sands were simulated satisfactorily. In addition, procedures for calibrating the model parameters are suggested to make the established model more reliable.