Identification of the Gas Explosion Hazardous Area in a Gob by Numerical Simulations─A Case study of the 6310 Working Face of Tangkou Coal Mine

In the process of coal mining, gas explosion accidents occur frequently, which seriously affect the safety of mine production. Identifying the gas explosion hazardous zone in a gob is of specific guiding significance for the prevention and control of gas explosion in a coal mine. In this work, we analyze the porosity and gas concentration distribution in the gob after the working face was mined by combining the particle flow and finite-element simulation. A trianglular gas explosion hazardous zone is obtained by multielement coupling, and the CO₂ injection simulation is then performed to eliminate the hazardous zone. The results show that the upper part of the gob and the edge of the return airway in the lower part are highly porous, and the porosities of other areas are relatively low with a value of 0.4. The gas concentrations in the upper left part and lower right part of the gob are relatively low, and the oxygen concentration distribution is the opposite. The gas explosion hazardous zone is mainly distributed near the oxidation zone. Yet, the simulation results reveal that after an injection of 97.5 m³/h of CO₂, there is no area in the goaf that meets the gas explosion concentration conditions, that is, the oxygen concentration is greater than 12% and the methane concentration is greater than 5% but less than 16%, which can effectively eliminate the gas explosion hazardous zone.