Post-Yield Properties of Rock Salt Using the Concept of Mobilized Strength Components and the Dilation Angle

Abstract

Post-yield strength and deformation characteristics of rock salt are of great significance in the analysis of progressive failure and convergence of rock surrounding the deep underground storage areas. The post-yield stress state of rock salt is assumed to satisfy the Mohr–Coulomb strength criterion, and a dilation angle can be used to describe the volumetric deformation. The post-yield mobilized cohesion, internal friction angle, and dilation angle were obtained based on the complete stress–strain curves under different confining pressures. The post-yield evolution laws of strength components and the dilation angle of rock salt were studied. A nonlinear cohesion weakening–friction strengthening model and a dilation angle model with respect to the equivalent plastic strain and confining stress were proposed using nonlinear fitting methods. The new models were then implemented into the FLAC3D software to verify that they could capture the post-yield strain hardening/softening and volumetric behaviors of rock salt reasonably.