Abstract: To solve the problem of spontaneous combustion of boreholes caused by poor sealing of boreholes in bedding extraction in No.10 Coal Mine of Pingdingshan Coal Mine, the stress distribution characteristics of surrounding rock of roadway were studied by means of drilling cuttings method, the leakage passage around boreholes and the conditions leading to spontaneous combustion of boreholes were analyzed in depth, and distribution of air leakage velocities around boreholes as a function of both sealing depth and sealing condition was simulated by using the Comsol Multiphysics software. Optimum sealing parameters were obtained and their effects on gas extraction were discussed. The results show that 0-7 m away from the roadway is the broken area, 8-19 m is the plastic area, 20-28 m is the elastic area, the broken area around the roadway, the air leakage around the borehole, the air leakage of sealing material and the air leakage of the extraction pipeline are the air leakage ways of the borehole, providing the ventilation and oxygen supply conditions for the spontaneous combustion of the borehole, that when the sealing depth is 17 m, the sealing length is 8 m, the maximum negative extraction is achieved, and when the pressure is less than 30 kPa, it can not only guarantee the effect of drainage but also prevent the spontaneous combustion of boreholes, and that volume fraction of single hole gas drainage reaches 70% after optimization of sealing parameters, which can effectively prevent spontaneous combustion of drainage holes.

Key words: gas extraction, spontaneous combustion, alone coal seam borehole hole sealing parameters, numerical simulation