Simulation Experimental Study On Surface Subsidence And Overburden Movement Law Under Thick Loose Mining Conditions

With the rapid development of China's national economy,the demand for coal is also increasing.However,while coal resources provide power for national economic construction,its mining process is bound to cause surface subsidence,triggering a series of environmental problems,such as construction.The cracks and collapse of the object,the deformation and subsidence of the road,and the loss of the groundwater body have caused considerable losses to the national economy.Therefore,the research on the mining subsidence problem has important theoretical and practical significance.This paper aims to solve the subsidence problem of the surface after the coal mining in the 11111 working face of the Pansidong Mine in Huainan,and not only uses the FLAC3D software to create a numerical model,but also explores the different progress of the working surface.The law of surface deformation and movement under different load conditions;the similar material model was also used to establish a similar material model to explore the movement law of overlying strata in the working face;and provide the basis and method for the mining subsidence engineering practice in the thick loose layer mining area The conclusions are as follows:(1)During the 11111 working face propulsion process,the maximum sinking value of the surface is always directly above the first mining goaf,and the sinking speed is proportional to the amount of coal seam propulsion.The stress balance achieved after the excavation of the upper working face is broken,the stress of the top plate and the bottom plate of the working face is re-stress adjusted,and the stress reduction zone on the goaf of the upper working face is offset,gradually pushing toward the center,when the lower layer works The range of the stress reduction zone is maximized when the surface is advanced to the maximum distance,and is symmetric about the center of the goaf.The stress in the stress concentration zone on both sides of the working face also increases as the pushing distance increases.(2)The magnitude and velocity of the surface displacement are proportional to the load pressure.As the load pressure increases,the arch shape inside the model increases continuously,and the influence on the surface subsidence basin is also increasing.The range of the stress concentration zone in the center of the zone is continuously increasing,gradually approaching the center of the goaf,and the range of the stress reduction zone above the goaf is continuously decreasing.(3)When the mining propulsion distance does not reach the ultimate span of the roof,the rock layer above the main key layer does not basically move.When the mining propulsion distance reaches the ultimate span of the roof,the main key layer is subjected to the loose layer and the overlying rock from above.The pressure is getting bigger and bigger,the bending deformation begins,the sub-critical layer is broken,the rock between the main key layer and the sub-critical layer produces a lot of cracks,and the rock mass subsidence above the main key layer also increases rapidly.(4)When the initial mining,the key layer hinders the upward transfer of the coal mining space,resulting in the surface subsidence displacement being too small.During the recovery,the key layer is subjected to the pressure exceeding the limit,and a great deformation occurs.The rock formation above it is rapid.Sinking,this is part of the reason why the amount of sinking during complex mining is greater than the amount of sinking in the first mining.Figure[56] Table[3] Reference[62]...