Gas Emission Characteristic and Control Technology for the Mining of Close-Distance Seam Group Under Complex Geological Conditions
Under the mining condition of close-distance seam group and high gas,significant changes in the thickness and spacing of adjacent coal seams lead to strong unevenness in gas emission,which has became a difficult problem for gas control in working faces.Taking the 2502 working face of Shaozhai Coal Mine as the research object,the failure depth and evolution characteristics of the underlying coal rock fracture zone were studied through theoretical analysis and numerical simulation.Based on the analysis of the gas migration law of adjacent coal seams,a calculation method for the gas emission quantity of close-distance seam group mining under complex geological conditions was proposed,and the gas emission quantity was predicted and divided into regions.Based on the prediction results of gas emission,a targeted method was proposed to extract depressurized gas from below adjacent layers and gas from goaf using drilling through floor,high-level drilling,and upper corner pipe insertion,achieving regional control of gas extraction.The results show that the 2502 working face of Shaozhai Coal Mine can be divided into three gas emission regions,with maximum gas emission quantity of 34.74,14.66,and 29.86 m3/min,respectively.After the regional control of gas extraction,the drilling through floor has a good effect on gas extraction,and the volume concentration of gas in the return airflow and upper corner decrease steadily without sudden changes.The gas control technology has a fine comprehensive control effect,effectively ensuring the safe mining of the working face.
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