A Progressive Failure Model of Deep Rocks Based on Plastic Hardening and Dilatancy Characteristics

Abstract

In order to study the progressive damage process and damage evolution law of deep rocks, conventional triaxial compression tests were conducted on sandstone, sandy mudstone, and mudstone under different loading conditions using the RMT-150C electro-hydraulic servo rock mechanics test system. Analyze the stress–strain characteristics of rocks, the deformation characteristics of progressive damage at different stages, and the strength characteristics of rocks under different loading pressures. Introduce equivalent plastic strain as a unified independent variable, analyze the nonlinear evolution law of rock strength parameters (c and φ) and expansion parameters (ψ) with equivalent plastic deformation, and establish a progressive rock damage model considering plastic hardening and expansion characteristics through rock strength parameters and expansion parameters. The results indicate that the progressive damage process of rocks can be divided into five stages: pore compression and density, linear elastic deformation, stable crack propagation, unstable crack propagation, and postpeak deformation. The strength of rock samples is mainly provided by the cohesive force parameter c, and the shear expansion angle ψ gradually increases and then stabilizes with the change of equivalent plastic strain ε_p. By fully considering the strain-softening and dilatancy characteristics of rock, a progressive damage evolution model for rock cohesion c, internal friction angle φ, and dilation angle ψ was theoretically developed. The accuracy of the model was verified through discussion, providing better theoretical guidance for practical rock engineering practice.