Influence of coal-rock interface inclination on the damage and failure law of original coal-rock combination

Abstract

In recent years, China's coal mines have gradually entered into deep mining. Ensuring safe and efficient extraction of deep coal resources has emerged as a key concern in the coal mining industry. The characteristics of the coal-rock interface play a significant role in influencing the damage and failure of the coal-rock combination. In order to deeply study the influence of interface inclination on the damage and failure law of the primary coal-rock combination, this paper successfully established the three-dimensional reconstruction model of the coal-rock combination with 5 different inclination angles (0°, 30°, 45°, 60°, 90°) by combining CT technology and AVZIO software. Then PFC2D software was used to simulate the damage and failure of coal-rock combination under different interface angles. The results show that: the loading damage characteristics of coal-rock combinations with different dip angles are similar, that is, the fracture evolution of coal-rock bodies is mainly concentrated in the coal bodies, and the damage and failure of coal-rock interfaces are the most severe. In the early stage of the loading damage, the fractal dimension of the coal-rock combination increases with the increase of interfacial inclination, but the growth rate of the fractal dimension shows a decreasing tendency with the increase of interfacial inclination. With the increase of the inclination angle of the interface of the assemblage, the growth rate of the acoustic emission signal and the total cumulative acoustic emission of the coal-rock combination show a tendency of increasing firstly, then decreasing and then increasing again. The porosity near the coal-rock interface is relatively large when the coal-rock combination is damaged by a load.