Study On Development Height Of Water Conducting Fracture Zone In Wangwa Coal Mine

China is rich in coal resources under water bodies,but for a long time,the safety of fully mechanized top coal caving in thick coal seams under water bodies has been one of the problems encountered by China’s coal industry.The study of the development height of water conduction fissure zone is to achieve safe mining under water bodies and improve coal resources.Recovery rate and protection of water resources are of great significance.Therefore,this paper takes Wangwa Coal Mine 5 coal 11 mining area as the research object,comprehensively applies theoretical analysis,on-site measurement,solid-liquid coupling similarity simulation and numerical simulation and other research methods to study the development height of water conduction fracture zone in fully mechanized top coal caving mining.Based on the analysis of geological borehole data and laboratory mechanical experiment results,the lithology of the overburden rock in the study area is classified as weak.Based on empirical formulas and key layer theory,the development height of the water conducting fracture zone is predicted;two For ground drilling,the development height of the water-conducting fissure zone was measured on-site by means of drilling fluid loss,water level observation,core engineering geological cataloging,etc.,and the development height of the water-conducting fissure zone in the 11 mining area was 166.82～175.40m,The curved subsidence zone developed to the surface.The solid-liquid coupling similarity simulation test reveals the characteristics of overburden rock failure in the goaf and the seepage rule of the reservoir water body affected by mining.The initial development height of the water-conducting fissure zone gradually increases with the advancement of the working face.Basically,it will no longer continue to develop upwards.The maximum development height of the water conduction fracture zone is 181.2m after the mining of the working face is completed.During the mining process,the reservoir and the dam are slightly damaged,resulting in increased infiltration of the reservoir water,but the clay is effectively separated.The water layer has not been destabilized;using FLAC3D numerical simulation software to further analyze the evolution process of the water-conducting fracture zone,the results show that the deformation and failure of the overlying rock are not developed overnight,but develop layer by layer from bottom to top.The"saddle" shape is basically consistent with similar simulation test results.Combining the research results of various methods,it is finally determined that the overburden failure characteristics of the 5th coal and 11th mining area of Wangwa Coal Mine have a complete "three-zone" distribution,and the maximum development height of the water-conducting fissure zone is 181.2m,which is 20.1 times the coal thickness.The shape is"saddle" shape,and the curved subsidence zone develops to the surface.The maximum subsidence value of the surface is 3300mm.After calculation,the number of waterproof safety coal pillars should be no less than 199.2m.The research results provide a basis for the safe mining design of Wangwa Coal Mine.