Failure Behaviors of Anchored Rock Mass with Various Fracture Inclinations in Tunnels

In natural rock mass, the existence of joints or fissures makes the strength of surrounding rock significantly reduced. In this paper, the influence of deformation and failure law of jointed rock mass on the stability of surrounding rock is studied by prefabricating five kinds of single fracture rock samples with different angles. Firstly, the failure and deformation of the unanchored and anchored specimens under different loading conditions (uniaxial compression and cyclic loading) were studied in laboratory tests, respectively. Secondly, the microscopic fracture characteristics and deformation damage modes of the specimens were simulated by using PFC numerical simulation software. The results show that the peak strength and elastic modulus of the sample increase with the increase in the inclination angle. After the sample is anchored, the peak strength of the sample is effectively improved, and the number of cracks is significantly reduced. In practical engineering applications, bolts can change the crack propagation mode and limit the initiation of cracks in the surrounding rock. By studying the crack propagation law and failure characteristics of fractured anchored rock samples, we can deepen the understanding of rock fracture behavior and better reveal the failure and deformation mechanism of surrounding rock instability in tunnel construction.