Rock Cutting and Crack Propagation of Jointed Rock Mass Within Rough Fractures Based on Point-Splitting Process

The rock is the direct object of disc cutter rock-breaking engineering. It contains natural joint surface. To investigate the influence of joint-surface roughness on the rock-breaking process. The hob model is created using AutoCAD software. The single- and twin-hob rock-breaking processes in intact rocks are simulated with PFC (Particle Flow Code) software. Furthermore, a rough joint network model is established based on MATLAB platform. The influence of joint-surface roughness on failure mode, crack propagation, and rock-breaking load is examined. The results reveal that cutter spacing in intact rock markedly governs the trends of rock-breaking load and crack count. The damage zone extends from the disc cutter–rock contact surface into the specimen interior. The rock-breaking process is mainly dominated by shear cracks. Fracturing of the rock mass occurs along the structural plane, and the force chain and crack propagation mainly distribute through tensile cracks. The initial structural plane of failure gradually penetrates the rock mass surface, resulting in the failure zone development. While considering joint roughness, the RDFN (Rough Discrete Fractures Network) model exhibits higher disc cutter contact force than the DFN (Discrete Fracture Network) model. Throughout the rock-breaking period, both RDFN and DFN models intersect in the number of cracks, but the difference between the two models remains significant. The contact force of the cutter in the RDFN and DFN models differs from that in whole rock. These findings offer a useful reference for elucidating the hob-breaking mechanism in jointed rock masses.