Study on influencing factors of gas emission in horizontal sub-level mining face of steeply inclined and extra-thick coal seam

The problem of gas emission in the working face of steeply inclined super thick coal seam has seriously affected the safety production of coal mines,so it is very important to study the gas emission in the working face of steeply inclined super thick coal seam.In order to study the influence of various factors on the gas emission in the working face of steeply inclined super thick coal seam,the prediction model of gas emission in the working face of steeply inclined super thick coal seam was constructed by using the method of sub-source prediction.Wudong Coal Mine +575 m horizontal No.45 coal seam west wing working face gas emission source was analyzed and the gas emission volume of the working face was predicted.The modified Morris screening method was used to analyze the sensitivity of various factors affecting gas emission in the Wudong Coal Mine +575 m horizontal No.45 coal seam west wing and No.43 coal seam west wing mining working face.The prediction results of the prediction model are in high consistency with the measured results.The maximum relative error is 5.43%,the minimum error is 0.18%,and the average relative error is 3.23%,which verifies the accuracy of the prediction model.The gas emission in the mining face mainly comes from the mining section and the lower coal body,while the gas emission in the adjacent coal seam and the upper goaf area is less.The sensitivity analysis results of the working face in the west wing of the +575 m horizontal No.45 coal seam are generally consistent.The coal loss gas emission coefficient of the working face,the gas emission of the mining seam,the original gas content of the coal seam,and the gas content gradient of the mining coal seam are all highly sensitive parameters,and the surrounding rock gas emission coefficient and the layered gas gushing coefficient are all sensitive parameters.The mining-influenced damage depth is a medium sensitivity parameter,and the gas emission coefficient of the old gob is an insensitive parameter.