Analysis On Gas Migration And Extraction Of Mining 8# Mine Layer In Changping Mine

With the increasing of requirement of coal quantity and quality,the workplace of mining in our country has changed from shallow area to deep underground space. Close distance coal seam group mining accounts for a large proportion of coal mining in our country,and it has the feature of high gas pressure, low permeability and high ground stress when compared to the mining of shallow area.By mining the adjacent close distance coal seam group,the gas existing in the coal layer will be emited, and it will transport into the working space.The total quantity of gas from adjacent coal layer and goaf area will cause a threat to the working space and it will place a heavy burden on the production safety.Reliefing gas pressure of close coal seam can guarantee that the mining of coal layer will obtained the positive effect of safety,high productivity and high efficient.In the view of lower protective layer mining in the close distance coal seam group,taking the 84301 working space as the research object,by using the method of theoretical analysis,experience research,and numerical simulation,we can get the result of the migration law of strata over goaf,the distribution law of gas in the goaf,and the effect of extaction of gas in the goaf. On the basis of Diffusion Law and Darcy law, we can obtain the result of the migration law of the 84301 working space methane in raw and coal layer.The FLAC3D numerical simulation software is used to simulate the mining process of the 84301 working space.When the working face is tunneled a few distance,we can get the analysis of rock stress, and deformation of strata over the goaf.By using the numerical simulation software of FLUENT,we can know the distribution law of gas in the "U+L" double inlet lanes and single return ventilation system in the 84301 mining face.The essay describe the distribution law on the plane which obtained from the direction of face forward,vertical.and tilt,by which we can provide the conference of choosing the spot of gas extraction.By considering the trait of close distance coal seam of Changping mining face, UU+L" ventilation system and high extraction lane is used to curb the relief gas emited from the upper coal layer.By changing the position of high extraction lane and by contrasting the gas concentration in the working face.we can choose the most effective spot for extracting gas.