Gas Drainage Technology in Goaf with Large Diameter and High Rock Trend Drilling

Taking 1302 fully mechanized caving face of Weijiadi Coal Mine as the research object, aiming at the characteristics of large gas emission and frequent gas exceeding limit during mining, this paper analyzed the difficult problems of gas control in working face, determined the theoretical height of caving zone and fissure zone of working face according to the gas cascade control mode formulated by Weijiadi Coal Mine and the principle of pressure relief gas, and inspected the "three zones". The reasonable horizon and arrangement of drilling holes along the strike of large diameter and high position rocks are determined. The field practice results show that the gas extraction technology of large diameter and high rock trending borehole has good extraction effect, the maximum gas concentration is 26.5% and the maximum gas extraction volume is 14000 m³. It effectively solves the problem of return air flow and upper corner gas exceeding the limit. The gas concentration of return air flow is basically kept at 0.2%∼0.25%, which ensures the safety of mine production.