| In the process of coal production in China, it tend to produce some harmful gases, such as methane, what have become a serious threat to coal mine work safety are that gas outburst and it’s transfinite in the upper corner at goaf. Along with the development of China’s coal industry, coal mining from the original low gas geological conditions simple mine expand to the high gassy mine with complex geological conditions, more and more gassy mine appearred, therefore, gas emission caused by mining is rising year by year, the gas not only pollutes the air but also contributes to the greenhouse effect in the atmosphere. So the gas harnessing can reduce greenhouse gas emissions, protect the ecological environment, and can reduce mine ventilation pressure, improve the safety of underground mining. Du Er-ping mine is a gassy mine, the average spacing between8#and9#coal seam of the mine is9m, it is a typical mining in close distance coal seam group,8#,9#coal seam working faces mostly adopt "U" type ventilation, which can reduce the amount of roadway driving and ensure the normal order of the working face. During the8#coal seam backstopping, methane in8#and9#coal seam flow at the same time, the work face appears the phenomenon of gas overrun,and it will influence the normal production.Aimed at the mining situation of8#coal seam of Du Er-ping coal, respectively for coal seam group mining stress field, fracture field and gas flow field, this paper has carried on the quantitative research. From mining stress field of coal seam group analysis unloading zone in the recovery process for8#coal seam, preliminary mastered the stress and strain state of surrounding rock and the plastic damage area at8#coal seam of Du Er-ping. Then according to the rules, under different stress state, how native fracture develop and extend, corresponding numerical model is established for the research the fracture evolution rule of coal seam group. It is obvious find crack concentricity areas at roof and floor in8#coal seam from graph, master the gas flow tendency in the surrounding rock fracture and gas flow all regions, find gas enrichment area; According to the laws,which the coal seam group mining fissure develop and evolve, analysis the gas source and quantify all sources. Simulate using "U" type ventilation only in the process of extraction, get cloud image and contour map about gas concentration in the goaf. Analysis the areas had high concentration gas exist in the fracture zones overburden of coal seam, puts forward the highest areas of gas concentration in the distance of working face high45m, return air lane inside30to40, use the simulation method verify the feasibility of gas emissions lane, which provides theoretical basis for goaf governance.Put forward the comprehensive control scheme,"the drainage of coal seam,gas discharge lane in fissure zone, layout extraction buried pipes in mining area, and carried out in68301,68303,68304working face in Du Er-ping. Quantity of gas drainage averaged20.71m3/min in face, the average extraction rate was54.08%, treatment effect is obvious. Illustrate that, through the analysis of coal seam group mining stress, fracture field, the gas flow field and the relationships among them, it can provide certain theoretical basis for gas control in theory. |
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