Technology of Uniform Pressure Sealing Gas Drainage in Fissure Development Area

Based on the seepage theory, the distribution model of the negative pressure in the coal seam cracks during gas extraction is deduced, and the gas drainage technology of equalizing pressure and sealing holes in the borehole along the seam is proposed for the first time. The sealing technology adopts double negative pressure for pumping, and the main and secondary pumping chambers are formed in the drilling hole by using the bag-type sealing device, under the joint action of the negative pressure generated by the main and secondary pumping chambers, the negative pressure in the coal seam cracks will be distributed twice, which reduces the pressure difference between the main pumping chambers and the external environment. At the same time, the negative pressure generated by the auxiliary pumping chamber will have a shielding effect, which preventing air flow to the main pumping chamber, thus reducing air leakage in the pumping process, and achieving the purpose of improving gas drainage concentration and efficiency. The field test of gas drainage technology of equal-pressure sealing hole was carried out in 12033 transportation lane of Zhongling Coal Mine. The average gas concentration of the traditional pore sealing process (polyurethane pore sealing)was 30.67% at the initial 5 d, 21.44% at the 10 d, and 65.69% at the average gas drainage concentration at the 0 to 50 d.