Exploring damage evolution of rock under different penetration and cutter spacing conditions using finite-discrete element method

Studying the damage evolution law of rock with directional bedding structure during the rolling cutter rock-breaking process under high confining pressure is of great significance. Previous damage studies have mostly been based on single finite elements or discrete elements, which make it difficult to capture the initiation and propagation of nonlinear cracks. Therefore, the coupled finite-discrete element method (FDEM) was used to establish a model for rock having a directional bedding structure. By comparing the damage cloud and crack distribution characteristics of cutter during penetration and rolling under different conditions of confining pressure, the effect of confining pressure and directional bedding angle on rock-breaking by cutters is demonstrated. The results reveal a notable confining pressure and bedding plane structure dependence on rock-breaking. Because the strength of the bedding plane is less than that of the rock matrix, the number of failure units along the direction of the bedding plane increases during the penetration process, and the rolling force oscillates periodically during the rolling process. The existence of confining pressure not only changes the distribution area of crack-dense area (CDA) and crack diffusion area (CDZ), but also changes the direction of propagation of the micro cracks.