Failure mechanism and control technology of the surrounding rock of the coal pillar crossing abandoned roadway

In order to solve the problems that the fully-mechanized mining face passes through the abandoned roadway under the condition of recovering the coal pillar of the recovery roadway, it is easy to cause the pressure frame, the large area of roofing in the middle of the working face and the stability of the coal wall., this paper took the No.6-2116 fully-mechanized working face passing through 8 lanes as the engineering background, and analyzed the No.6-2116 fully-mechanized working face with the combination of theoretical analysis, FLAC3D numerical simulation and field engineering measurement. Based on the theoretical analysis, it is determined that the strength of the filling body should be greater than 5.17 MPa, which can ensure the smooth passage of the working face through the roadway, and the backfill body can maintain the stability of the surrounding rock of the roadway;through FLAC3D numerical simulation, it is determined that the strength of the filling body is 10.5 MPa, which is the most appropriate; through the field industrial test, it is comprehensively compared that the coal-cement filled wood buttress is connected to the roof and the high water quick setting material is filled. The method of anchor cable and shaped steel shed support and so on has advantages and disadvantages on surrounding rock control. Finally, the support method of coal powder cement filling with wood crib is determined. The support effect of this method is basically consistent with the strength of high water quick setting material, which can save the cost of filling and support to the greatest extent, and also reduce the subsidence in the middle of the roof. The coal wall at the intersection of the main roadway and the connecting roadway has also remained stable, which can effectively ensure the normal advance of the fully-mechanized mining face.