Study on reasonable gas extraction radius based on multi-index and multi-method

The gas extraction radius is affected by coal seam gas pressure, borehole diameter, extraction time, extraction negative pressure and other factors. Under the coupling of different factors, the gas extraction radius of borehole is also different. For complex under the condition of the shortage of the radius of the gas extraction method, combining with TianAn comes up out of no. 3 coal mine coal seam gas occurrence and mining conditions, puts forward the method of pressure drop and gas flow method, combination method of determining the radius of the gas extraction, analysis of the 1∼3 m, 4 m and 5∼6 m extraction under the condition of radius of influence range, ultimately determine the radius of extraction for 3 m, It can not only meet the gas extraction rate of working face, but also ensure the safety of production and efficient utilization of gas.