Experimental Study on the Determinant Factors and Energy Criterion of Coal and Gas Outbursts

A series of coal and gas outburst tests were conducted on coal seams in north China to determine the important order of gas pressure, in situ stress, and coal strength during coal and gas outbursts. And the typical phenomena of coal and gas outbursts were investigated. In addition, improved outburst energy equations were built to study the coal energy evolution process during coal and gas outbursts. The results show that the coal strength has the strongest influence on coal and gas outbursts, followed by the gas pressure and the in situ stress. The weights of pulverized coal with a particle size of less than 0.28 mm are consistent with the changing trend of the total weights of the pulverized coal particles in the corresponding outburst interval. Furthermore, the results suggest that the gas pressure monitored by the sensors close to the outburst hole begins to drop first and lasts for the longest time. The outburst coal presents obvious fracture and pulverization damage characteristics, and the pulverization damage features of the coal near the outburst hole are more obvious. In addition, the improved outburst energy equation was established, and the rationality of the improved outburst energy equation was verified by using the outburst orthogonal simulation experimental data and the on-site outburst accident cases. The results of this experiment have important guiding significance for preventing and controlling the occurrence of coal and gas outbursts and ensuring safe and efficient mining of coal mines.