Mechanism of fault rockburst-induced coal and gas outburst: Mine accident’s reconstruction via a coupled model of compound disasters

The rockburst and coal and gas outburst (CAGO) problems aggravate the annual coal mining depth increase. In high-gas mines, these two hazards usually coexist, and their interaction may result in unpredictable sudden disasters. This paper studies a real dynamic accident of coal mass ejection caused by rockburst in a particular coal mine located in the Anhui Province, China. This study innovatively combines geomechanics and the numerical simulation to analyze the energy distribution near a normal fault, revealing how stress superposition triggers compound disasters. Key findings include the identification of a high-energy accumulation region 20 m from the fault and the demonstration that gas expansion energy alone is insufficient to trigger outbursts without rockburst-induced stress. The features of the dynamic disasters and their interaction are discussed in detail. The CAGO mechanism induced by a normal fault under the mining-induced influence is explored using the geomechanics approach. A numerical simulation model of fault is proposed to assess the energy distribution features in the fault vicinity. The relationship between energy generation and dissipation during CAGO is derived. Finally, the mechanism of compound dynamic disasters of CAGO and rockburst is reported, and the corresponding prevention and control measures are discussed. The superposition of concentrated stress in the fault and the mining-induced bearing pressure triggers the rockburst in the mining accident under study. The impact energy generated by the rockburst and the gas expansion accompanying this process can surpass the energy dissipated by the outburst. The coal and rock masses are damaged and ejected into the roadway at high speed, causing dynamic disasters.