Determination of influence radius of hydraulic punch extraction by gas emission attenuation characteristic method

It is of great practical significance to determine the influence radius parameters of gas drainage by hydraulic punching through strata for improving the gas drainage efficiency, eliminating the gap between the drilling holes and ensuring the safety of coal mines. This paper studied and analyzed the influence of coal loose around the borehole on gas emission, and the characteristics of gas flow and emission from the borehole under negative pressure extraction. The negative power exponential equation of borehole gas emission calculates the gas emission in the early stage and the limit gas emission in the later stage respectively, and the sum of the two improves the accuracy of calculation and solution for the limit gas emission in the borehole; It is pointed out that the flow direction of coal gas around the drainage hole under the influence of negative pressure extraction is the reason for the sudden reduction of gas emission attenuation coefficient at the later stage of the drainage hole, resulting in a significant difference between the gas emission limit of 100-meter borehole of the drainage hole under the influence of negative pressure extraction and the one that has not been affected by the drainage; According to the abrupt change of gas gushing attenuation coefficient of discharge boreholes affected by negative pressure drainage and the significant difference of gas discharge limit of 100 meters of discharge boreholes, a characteristic method of gas gushing attenuation coefficient is proposed to determine the influence radius of hydraulic punching drainage. Using this method, the field test was carried out in Hebi Zhongtai Coal Industry. The results show that the average amount of coal flushed out of the coal hole is 1.3 t/m, the extraction time is 60 days, and the extraction influence radius is 5.1 m.