Study on macro–micro mechanical behavior of rock like samples with hole and cracks

Abstract

There are many holes and cracks in the rock, which significantly affect the strength of the rock mass. In this paper, the influence of holes and crack spacing on the uniaxial compressive strength and failure mode of rock samples with holes and cracks is studied. Through uniaxial compression testing, the macroscopic mechanical behavior of rock-like samples is summarized. Based on the experimental results, the microscopic parameters of the numerical model established in PFC^3D are calibrated. Then, the uniaxial loading process is simulated to verify the numerical model. According to the simulation results, the influence of holes and crack spacing on the micro-failure mechanism of rock-like samples is analyzed from the perspective of mechanical properties, particle displacement, and failure mode. The results show that the uniaxial compressive strength and elastic modulus of the sample with holes are lower than those of the intact sample, but higher than those of the sample with single hole and double cracks. As the spacing between cracks increases, the peak strength and elastic modulus of the sample show a trend of first increasing and then decreasing. The maximum displacement of particles and the number of microcracks both show a trend of first increasing and then decreasing. During the loading process, there is a phenomenon of stress concentration on both sides of the hole and the crack tip, which can generate a large number of microcracks. Acoustic emission events can be divided into three stages: silent emission stage, stable stage, and rapid growth stage. The damage evolution process of the specimen can be divided into three stages: no damage stage, stable damage growth stage, and damage failure stage.