Obtaining the bursting liability is essential for rock burst mitigation. To reasonably evaluate the bursting liability of coal in deep coal mining, a new modified bursting energy index considering rebound and damage effects of rock is proposed. Then, uniaxial compressive tests of gypsum–rock combination specimens with different rock types are conducted for researching the energy evolution and bursting liability. Third, the traditional bursting energy index K_E and modified bursting energy index K_ED are compared. At last, the reasonability of K_ED is verified through PFC2D simulation. Results show: (1) When evaluating the bursting liability of coal–rock combination, the rebound and damage effects of rock must be considered. (2) The uniaxial compressive strength of gypsum–rock combination specimen nonlinearly increases with increasing rock strength, but the dynamic failure duration exponentially decreases. (3) K_E and K_ED all increase linearly when the rock strength increases. (4) The slope of fitting curve of K_ED is smaller than that of K_E, indicating that the bursting liability calculated by K_E is strengthened. (5) PFC2D simulation shows that K_ED decreases with increasing number of drilling hole in the coal component. When using K_ED to evaluate the bursting liability of coal–rock combination, it is more reasonable and applicable.

The collapse of overlying rocks caused by the instability of residual coal pillars during lower coal seam mining significantly impacts its safety. This paper focuses on the gentle dipping coal seam group and utilizes the discrete element method (DEM) as the basis to comprehensively consider multiple factors through orthogonal experiments. In so doing it reveals the influence mechanisms of various factors on mining at a close distance under a residual coal pillar. Firstly, the process of lower coal seam mining under residual coal pillars in gently-dipping coal seams was simulated and analyzed based on a case study at the Baoping coal mine. Comparing the evolution characteristics of coal–rock fractures, stress changes, and displacement changes during the mining process reveals the mechanism of the joint instability of the lower coal seam, interlayer rock, coal pillars, and overlying strata under the disturbed conditions of lower panel mining. Secondly, an orthogonal simulation experiment was established using the width of the coal pillar and the thickness of the lower coal seam as variables. By comparing the development process of cracks, stress distribution, and rock displacement under different conditions, the research results indicate that the width of coal pillars has an impact on the maximum amount of coal pillar subsidence, while the thickness of the underlying coal seam has an impact on the time of subsidence, when h_d ≥ 4.2 m (h_j/h_d ≤ 4) and w ≤ 14 m (w/h_m ≤ 2), a large-scale collapse of the overlying strata of the coal pillar occurs.

In the mining process of an underground coal mine, the dynamic load often causes great damage to the roadway and affects the normal mining of coal mine. In this paper, the deformation of surrounding rocks under static load and different disturbance intensities is studied by numerical simulation. The results show that under the same static load condition, the greater the dynamic load strength is, the more obvious the roadway roof displacement subsidence is. With the increase in dynamic load propagation distance, the amplitude of the dynamic load waveform decreases gradually. Under the same disturbance load intensity, the variation of roadway displacement with different disturbance load frequencies is studied. According to the influence of dynamic load on the deformation of the roadway, a combined support plan of shotcrete anchor net and reinforcement anchor cable is proposed. Finally, the rationality of the optimized support scheme is verified by numerical simulation and field results. The results show that the combined support scheme can effectively increase the strength of the broken soft rock and reduce the deformation of the surrounding rock. At the same time, it releases the expansion energy generated by the mutual compression and deformation of the rock layers, effectively maintaining the long‐term stability of the roadway.