Mechanical behaviour and failure characteristics of rocks with composite defects of different angle fissures around hole

To study the mechanical properties of rocks with cracks of different angles around the hole, the particle flow discrete element software PFC2D and laboratory experiments were used to conduct uniaxial compression tests on rocks with cracks of different angles around the hole. The failure behaviour and mechanical properties of rock samples with cracks of different angles were analysed, the failure modes of rocks with defects of different angles were revealed, and the crack propagation and stress evolution of rocks with cracks of different angles were studied. The results show that compared with the intact rocks, the peak stress, elastic modulus, peak strain, initiation stress, damage stress, and other properties of fissure rocks with different angles around the hole are lower; the defect combination of different fissure angles around the hole has a substantial impact on the failure characteristics of rock samples-different fissure angles in rock samples produce different failure modes, resulting in different crack development and propagation processes. Through the comparative study of indoor experiments, the results of indoor real rock and numerical simulation experiments are verified, and the macroscopic failure characteristics of rocks are similar. This study can correctly understand the mechanical properties of fissure rocks with different angles around the hole and provide theoretical guidance for practical rock engineering.