Research On The Law Of Overlying Rock Failure In The Goaf Of Coal Mine

Coal mining subsidence disasters caused by goafs in coal mines are widely distributed and harmful.The various geological disasters and ecological damage induced by the old goafs have become important issues that plague the sustainable development of the mining areas in Fugu County.Therefore,this paper studies the overburden failure laws of coal mined-out areas in Fugu County in order to guide and plan local coal mining activities and subsequent goaf management.In this paper,with the help of experimental research methods such as geophysical methods and numerical simulations,the detection methods of the damage range and damage degree of the overburden in the goaf and the damage mechanism of the coal pillars and roof in the room and pillar goaf are studied;the mine rock layer control theory is introduced,The control effect of the key layers on the overburden strata and the destruction of the overburden in the mined-out area are studied,and the maximum development range of the “three zones” of the overburden is predicted;the surface subsidence characteristics are predicted based on the probability integral method and numerical simulation,Analyze the deformation and failure laws of the overlying rock.The main findings are as follows:In this paper,with the help of experimental research methods such as geophysical methods and numerical simulation,the detection methods of the damage scope and damage degree of the overlying rock in the goaf and the damage mechanism of the coal pillar and roof in the room and pillar goaf are studied;Mine rock strata control theory are introduced,the control effect of the key strata on the overburden strata and the failure rules of the overburden in the mined-out area were studied,and the maximum development range of the "three zones" was predicted;Based on the probability integration method and numerical simulation,the surface subsidence characteristics were predicted,the deformation and failure laws of overlying rock are analyzed.The main findings are as follows:(1)Using geophysical detection methods to study the geological structure of the mined-out area,by analyzing the results of the transient electromagnetic method and the audio-frequency magnetotelluric method,the apparent resistivity cross-section and plan view of the two methods are obtained for the damage of the overburden of the mined-out area.Reflecting the extent and the development range of the fracture zone,the collapse in the overburden of the mined-out area,the distribution area of the fracture zone and the approximate development height are analyzed;the application of the two geophysical exploration methods is analyzed.(2)Based on the means of mechanical analysis,the coal pillar failure mechanism of the overlying rock in the goaf of Zhangbaya Joint Coal Mine was studied,and the stability of the coal pillar and roof of the goaf under the current room and pillar mining was checked;based on the rock strata Control theory,discussed the position of the main and sub-key layers in the overburden of the 3-3 coal seam and the 5-2 coal seam goaf,their control range,and strength characteristics;discussed and studied the development law and development of the "three zones" in the overburden It also predicts the development height of the collapse and fracture zone,and combines the results of the key layer identification to analyze the deformation and failure characteristics of each layer of the overlying rock;the introduction of the laminated beam model in structural mechanics will provide a good The strength analysis and stability calculation of the overlying rock in the 3-3 coal seam and the 5-2 coal seam goaf were carried out.(3)Based on the probability integration method,the deformation characteristics of the 3-3 coal seam and the 5-2 coal seam at the current stage of room and pillar mining and the future mining area after the maximum surface subsidence,movement duration and maximum subsidence velocity are predicted.(4)By means of numerical simulation,the deformation and failure laws of overlying rock and the ground surface under the influence of different mining depths and different roof management methods are studied;the distribution range and distribution characteristics of the stress field in the overlying rock are discussed,and combined with the overburden The distribution range and failure form of the plastic failure zone in the rock,and the failure law of the overlying rock is analyzed.