Research On Gas Migration Rule In Mechanized Working Face And Goaf Under The Large Mining Height

Compared with general mining method, The mining height of large mining height comprehensive mechanical method is larger, Corresponding, The destruction of rocks in goaf is severe. Overburden damage to the formation of a large amount of wear layer and separation fracture when coal mining, Nearby coal gas under the function of pressure flows into goaf through these cracks, Part of the gas will flows into working face from goaf. Gas is affected by the impact of air leakage to accumulate in the upper corner position in the traditional U type ventilation, It severely affected to the safe production of coal mine.Thesis analysis of the destruction law of goaf and overburden affected by mining action on the basis of research results previous achieved and divide area of goaf, Analysis distribution of porosity of different regions in goaf, Determined the parameters and boundary conditions in different regions of goaf. Detailed analysis the flow state and pattern of the gas in the coal and rock by contact the characteristics of the porosity, Mathematical model of gas migration in goaf is builded according to the diffusion and penetration theory. To be more intuitive understanding of the gas distribution of different ventilation mode by using FLUENT software and theoretical analysis, Find the gas accumulation area in goaf and working face, provide a reliable basis for the gas prevention of working face.Detailed analysis of the gas distribution of goaf in the direction of vertical,working face tendency and advancing by numerical Simulation, The concentrations of gas in the upper corner is 5% in U type ventilation according to gas distribution of working face, It left a security risk to normal production of working face, we must take appropriate control measures.While use U+L ventilation mode, Although added a tail lane emissions,The gas concentration of upper corner is reduced, But it does not solve the problem, With the influence of other factors, the gas concentration is still easily overrun. When using the U+L+high pumping roadway, To furnished a high pumping roadway in the fractured area along the direction of coal strike is effectively reduce the gas concentration of upper corner by gas emissions role with end lane and high pumping roadway, The problem of gas concentration overrun is solved. When using U+median drainage lane, The negative pressure acted on upper corner, The gas concentration in the region is about 0.8%, The gas problem is easily solved. Compared to U+L+high pumping roadway, Amount of excavation roadwayproject is reduced, The cost of business is Saved. Through the test of the effect of gas treatment for the eight coal mine, it proved that to furnished median drainage lane along the direction of coal strike can effectively reduced the gas concentration of upper corner, To provide a reference of working face of gas treatment for similar treatment.