Numerical Research on the Instability Mechanism and Influencing Factors of Coal-Rock Structures

Abstract Coal-rock structures in deep coal-bearing strata, due to their intricate mechanical properties, are the primary carriers of rock burst hazards. This study, incorporating singular point catastrophe theory, develops a mathematical model of the coal-rock to investigate the instability mechanisms and influencing factors of these structures. The results reveal the following: (1) By integrating the sharp corner mutation model, the mathematical formulation of the failure criterion for the coal-rock composite system was derived. (2) The failure process of the coal-rock composite structure is gradual. The strength of the coal significantly influences the peak instability strength of the composite structure, whereas the strength of the rock has a relatively minor impact on it. (3) As the proportion of rock thickness decreases, the number of fractures within the rock also diminishes, with these fractures primarily developing on the side of the rock adjacent to the coal-rock contact surface. The findings of this research can serve as valuable references for the prevention of rockbursts in the protection of coal pillars.