| Coal as the dominant energy of our country in a considerable period of time can not be replaced. Whether the coal can be mined safely and efficiently, and seriously affect the healthy development of national economy of China. For a long time, the gas accident is the first killer that endangers the life of the miners, and the gas control has becoming a worldwide problem. At present, the shallow coal resources in our country are depleted day by day, and the coal seam mining is carried out to the deep part. With the increase of mining depth of coal seam, ground stress, gas pressure and content are becoming more and more highly, the quantity of gas emission increases obviously. The danger of coal and gas outburst is becoming more and more serious, and the difficulty of gas control is more and more serious. Safe and efficient coal mining is unable to realize if the problem of gas comprehensive control is not solved for a long time. Therefore, studying the law of surrounding rock activity in the process of pressure relief mining, exploring the process of the formation and development of the mining fissure and determining the location of gas enrichment area is the key to comprehensive gas control.In the paper, it is taken as an object of 1112(1) working face of One thousand meters depth of Zhuji Mine, studying the law of failure characteristics of surrounding rock during the coal mining, the distribution of vertical stress and the mining fissure formation and development evolution process by two ways of the 3DEC numerical simulation and the similar simulation experiment. The simulation results showed that while the immediate roof step distance is 20 m to 21.6m, the main roof caving step distance is 35 m to 36 m and the periodic-weighting interval is 10 m. The shape of formation damage was trapezoidal and upward and forward, and the formation had an uneven subsidence. Transverse and vertical fracture developed well when distanced from at 10~15 times mining height from the roof of mined coal. The working face boundary was less affected by mining about 35 m distanced from the working face cut-hole. The position of gas enrichment area in the vertical direction is 10 times mining height from the roof of coal seam, its width is about 30 m, and in the level from is about 15 m from the working face cut-holeAccording to the results of numerical simulation and similarity simulation experiment, and combined with the engineering practice, the multi-purpose roadway was constructed at about 10 times mining height than the roof strata and about 35 m outside the track roadway. And then the new gas comprehensive control mode including one roadway with multi-purposes was put forward. The results in the engineering practice showed that the return air volume of working face was 2100 to 2751 m3/min, the average of the air exhaust gas volume was 10.04m3/min, the average of the gas concentration was 0.4%, the gas extraction rate was 84.8%. The effects of different drainage were examined: the mount of average gas drainage of the multi-purpose lane, the ground well, the tubing buried in goaf and the airtight walls were 22.38 m3/min, 20.39 m3/min, 3.7 m3/min and 9.4 m3/min separately, which were 40.1%, 36.5%, 6.6% and 16.8% of the total drainage. At the same time, the effects of a-large-aperture drilling pump was examined, the single hole drainage quantity up to 9.84m3/min and the gas concentration came to 98.5%. The maximum of gas emission was 116.27 m3/min, and the average was 69m3/min. The average of coal output was 4746.61t/d and the cumulative coal production reached 2.34 million tons. This mode can achieve safely and efficiently simultaneous extraction of coal and gas of the high methane working face in deep coal mine. |
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