Study On Evolution And Distribution Of Mining Fracture Field And Gas Migration Law Of Unloading In Thick Coal Seam

Due to the complex and variability of mine geological conditions in China,the effect of gas drainage in most mines is not ideal.The study on the evolution law of the mining fracturing field and the law of gas displacement in the overburden is a study of coal and gas mining.The key point is to improve the extraction effect of the pressure relief gas.Based on the research of theoretical derivation,physical similarity simulation and numerical simulation,this paper studies the evolution of the mining fissure field and the migration and enrichment of internal pressure relief gas in the thick coal seam of Tianchi coal mine.The research results were applied to the site and the following research results were initially obtained:(1)According to the production geological conditions of Tianchi Coal Mine's thick seam working face,a two-dimensional physical similarity simulation test rig was built to study the deformation and failure law of overlying strata under the condition of thick seam mining.By dividing the distribution area of mining fissures,the quantitative analysis of mining fissures was carried out by using fractal theory,and the evolution law of mining fissures in thick seam was obtained.(2)According to the distribution characteristics of the evolutionary equilibrium state of mining fissure field in physical similarity simulation,the stress,displacement and fissure distribution law of mining overburden under different coal seam mining heights are studied by using UDEC two-dimensional discrete element numerical simulation software,and the pressure relief area,maximum displacement area and mining fissure distribution law of mining fissure field in thick coal seam under different coal seam mining heights are obtained.(3)According to the distribution characteristics of mining fissures in thick coal seam,a gas flow model of pressure relief in mining fissure field is established by using the theory of motion equation in fluid mechanics.The gas migration and enrichment process in mining fissure field of thick coal seam is analyzed by COMSOL Multiphysics multi-physical field coupling numerical simulation software,and the law of gas migration and enrichment in mining fissure field of thick coal seam is obtained.(4)Based on the above research results,the extraction technology of unloading gas in mining fissure field under thick coal seam mining conditions is determined,reasonable extraction parameters are put forward,and it is applied to on-site drainage engineering to analyze the extraction to high drainage roadway.The effect confirms the rationality of the extraction parameters and ensures the safe and efficient production of the mine.