A cohesive strengthening/damage-plasticity model and its application for DEM numerical investigation in hardening/softening of rock and soil

Abstract

In this study, a cohesive strengthening/damage-plasticity model (CS/DPM) based on the discrete element method (DEM) was proposed to better simulate the hardening/softening effect and shear dilatancy/shrinkage characteristic of rock and soil. Firstly, on the basis of the original cohesive damage-plasticity model (CDPM), a cumulative strengthening variable was defined to characterize the evolution of bonded contact stiffness and strength with plastic strain at the grain scale. According to the hyperbolic yield criterion, the critical stress state of the bond during the transition from elastic to plastic was determined. The strengthening and damage thresholds were introduced separately to control the extent of hardening and softening. On this basis, the shear shrinkage effect between particles was considered and incorporated into the development of the constitutive model algorithm as a stress return mechanism. Subsequently, a series of simulation experiments were carried out and the results were compared with the existing experimental or numerical solutions to verify the correctness and feasibility of the model. In addition, the impact of different contact parameters on the mechanical response was analyzed in a comparative manner to provide a reference for studying the hardening/softening behavior and failure mechanism of rock and soil from the mesoscopic scale.