Research and engineering practice of mining-induced pressure relief gas extraction of replacing roadway with borehole technology

In order to solve the gas treatment problem of upper corner and return air flow by "U"-shaped ventilation, based on the technical principle and advantage analysis of mining-induced pressure relief gas extraction of replacing roadway with borehole, the mining-induced pressure relief gas enrichment area was determined according to the overburden collapse law of the working face. The high-level directional long drilling of the roof was constructed at 520 m in the inner section of Ji₁₅-15050 working face of No. 8 coal mine of Pingmei Co., Ltd. to replace the high extraction roadway for mining-induced pressure relief gas extraction. The test results show that during the three months extraction period of directional drilling, the concentration of the upper corner and return air gas in the working face is maintained at 0.4% to 0.6%, the high concentration gas zone in the fracture zone of the roof in the working face is above 25 m vertically from the roof of the coal seam, the cost of gas treatment is 67.9% lower than that of the high level extraction roadway, and the treatment period is shortened by 2/3, which realizes goal of the mine safety production, cost reduction and efficiency increase.