Mine Pressure Characteristics And Reinforcement Support Technology Of Gob-side Roadway In Fully Mechanized Caving Face

Taking the II946 fully mechanized sublevel caving face of Luling Coal Mine of Huaibei Mining Group as the engineering background,the paper comprehensively uses the means of field investigation,theoretical analysis,numerical simulation and field monitoring to study the characteristics of the ground pressure of the gob side entry under the conditions of fully mechanized sublevel caving mining,reveals the deformation and failure mechanism of the surrounding rock of the gob side entry in the fully mechanized sublevel caving face,puts forward the reinforcement and support scheme of the gob side entry,and carries out field application.At the same time,the II946 coal seam belongs to the close distance coal seam,and its mining method belongs to the combined seam fully mechanized top coal caving mining.When the combined seam fully mechanized top coal caving mining is carried out in the working face,it is necessary to consider the influence of various factors on the top coal caving.The factors affecting the top coal caving property include the thickness and strength of the coal seam,the lithology and thickness of the roof,the thickness of the coal seam dirt band,etc.Using numerical simulation,the influence of different seam height on the deformation and failure of the gob side entry is studied.The main conclusions are as follows:(1)The working resistance of II946 fully mechanized top coal caving face and the hydraulic support at the end of two roadways is analyzed.It shows that there are differences in the ground pressure appearance at different positions of the face and at the end of two roadways.The upper area of the face(along the goaf side)comes first,the middle area comes second,and the lower area comes last;The advance of goaf side wind roadway and the ground pressure at its end are more severe,and the roadway deformation and damage are more serious;The average initial weighting step distance of II946 fully mechanized top coal caving face is 26.87 m,and the average periodic weighting step distance is 9.41 m.The influence range of leading stress is 110m～130m,and the peak value of leading stress is 23m～25m away from the working face.(2)The three-dimensional numerical model of II944 and II946 working faces is established by using FLAC3 D,and the stability of gob side roadway and section coal pillar in II944 goaf and II946 working face mining process is simulated and analyzed.It shows that with II946 working face advancing,the deformation and failure of gob side roadway are increasing,and the vertical stress of section coal pillar is increasing;This paper further simulated and analyzed the deformation and failure law of gob side entry in II946 working face under five conditions of mining 9 coal seams,9 coal seams+dirt bands,9 coal seams+dirt bands+81 coal seams+82 coal seams,9 coal seams+dirt bands+81 coal seams+82 coal seams+83 coal seams.It shows that with the increase of the thickness of the combined seam fully mechanized top coal caving,the displacement of the top and floor of the roadway along the gob side,the vertical stress of the coal pillar,and the plastic failure area of the section coal pillar increase;However,when the thickness of fully mechanized top coal caving in the combined seam increases to a certain thickness,the vertical stress of the section coal pillar increases first and then decreases,indicating that with the increase of the thickness of fully mechanized top coal caving in the combined seam,the section coal pillar is seriously damaged and the bearing capacity decreases.(3)From the perspective of active and passive support,the deformation and damage causes of II946 goaf side entry are analyzed,and the grouting reinforcement support mode,parameters and support scheme of II946 fully mechanized top coal caving face goaf side entry are optimized.The roof grouting anchor cable is 6.1m,which is arranged in "202" mode,and the row spacing is 1m;The roof grouting anchor bolt is 3.3m,which is arranged in "202" mode with a row spacing of 1m;The grouting anchor cable on both sides is 4.6m,which is arranged in "202" mode with a row spacing of 1.0m;The grouting anchor bolts on both sides are 3.3m long,arranged in "101" mode,and the row spacing is 1.3m.FLAC3 D is used to simulate and analyze the effect of reinforcement and support in the mining process of II946 fully mechanized top coal caving face.(4)The field monitoring results of the gob side roadway of II946 fully mechanized top coal caving face show that the slurry of the roadway roof coal strata is clearly visible after grouting reinforcement,and no new separation layer appears,and the fracture of the original separation layer is effectively blocked;After the reinforcement and support,the working resistance of the advance support and the displacement of the roof and floor along the goaf roadway decrease,the bearing capacity of the section coal pillar increases,and the stability of the surrounding rock of the goaf roadway is effectively controlled.Figure [144] Table [10] Reference [84]...