Research and Application of Pressure Relived and Permeability Enhanced Effect of Perforated Slotting Borehole on Coal

The mechanism of pressure relieved and permeability enhanced of slotting borehole in coal seam was analyzed by mathematical method. Based on the geological condition simulation of Pingbao Coal Mine, the optimal height and spacing of hydraulic slotting were 0.02 m and 4 m respectively. Field industrial tests were carried out to compare and analyze the gas extraction situation of slotting borehole and ordinary borehole. The results show that the gas extraction volume of slotting borehole is three times of that of ordinary borehole in 30 days, and the gas extraction concentration of slotting borehole is 2 to 3 times as that of ordinary borehole, and the gas concentration of slotting borehole can be maintained at about 80% for a long time; the monthly tunneling progress of subsequent roadways is raised to a range from 100 m to 120 m, which used to be between 60 m and 80 m, the tunneling efficiency increases by 30% to 50%. This technology can solve the problem of gas outburst in coal seam and promote the safe and efficient production of coal mine.