Shear Failure Mechanism and Numerical Simulation Analysis of Rock-like Materials with an Embedded Flaw

Abstract

In this study, the failure characteristics of self-made rock with internal flaws under shear were studied and a numerical simulation analysis was carried out. Firstly, based on basic physical and mechanical tests, the shear strength characteristics of rocks with built-in 3D defects were summarized. PFC3D simulation software was used to model the samples with flaws, and the microscopic parameters were calibrated according to the test results. From the simulation results, it was found that the generation mode of microcracks from the flaw tip was different. The microcracks of forward shear and reverse shear were mainly generated from the horizontal direction, while the microcracks of lateral shear gradually increased from the upper and lower ends of the flaw in the opposite direction. When the peak shear strength was reached, the total number of cracks was the largest in lateral shear and the smallest in forward shear. When studying the particle velocity vector field, it was found that when reaching the peak shear strength, the particles on both sides of the prefabricated flaw appeared to be in vortex motion. When α = 45° and σn = 2 MPa, the failure mode of forward shear and lateral shear was shear-tensile-shear (S-T-S), and that of reverse shear and the intact specimen was shear-shear-shear (S-S-S). The lateral shear tensile effect was the most obvious and was mainly concentrated in the middle part of the sample.