Research On Cutting Roof And Protecting Entry With Concrete Wallbeside The Goaf In Full-high-seam Mining In Wangzhuang Mine

JinNeng Wang Zhuang coal mining mainly adopts No.3 coal seam.The average coal thickness of No.3 coal seam is 5 m.which adopts full-high-seam mining.In order to reduce the loss of coal resources and improve the coal production rate,utilize the pillarless coal mining along the remaining walls,where is no coal pillar along the remaining between the 3503face and the 3505face.In the 3503 face,the wall is expanded in advance,and then the concrete wall is poured in the expanding area.When the 3503 face is stoped and the rock stratum activity in the goaf tends to be stable,it is close to the return lane of the3505 face with the concrete wall,so as to utilize the pillarless coal mining.Due to the mining of the 3503 face,the lateral support pressure is relatively high,The deformation and damage of the concrete wall is more serious.The difficulty of controlling the surrounding rock in the tunnel is more difficult and the maintenance is also difficult.In order to solve this problem,this paper puts forward the technical research on the cutting and pressure relief of the top and bottom wall of the large mining face.Through the laboratory experiment,the lithology and parameters of the roof and floor rock of the roadway are grasped.Through the theoretical study,the load of each stratified rock layer on the roof of the large mining height working face and the fracture characteristics of the lateral roof rock in the goaf are analyzed.Simulation calculation,verify the feasibility of cutting top and pressure relief roadway technology,and give the roof and pressure relief roadway scheme;through the field practice,to determine the purpose of achieving the pressure relief roadway.The main research conclusions are as follows:(1)Theoretical analysis of roof strata load and gob side roof rock breaking characteristics.The load theoretical calculation model of the retaining wall(concrete wall)is constructed,and the load calculation formula of the retaining wall(concrete wall)is given.The relationship between the load of the retaining wall(concrete wall)and the length of the lateral roof of the goaf is clearly defined.The length of the wall(concrete wall)and the position of the coal side is fixed,and the length of the base cantilever is the length of the cantilever.The longer the length is,the larger the load will be.On the contrary,shortening the length of the top cantilever can reduce the load on the retaining wall(concrete wall)along the goaf.(2)Based on the theoretical research and calculation results mentioned above,the stress situation of the retaining wall(concrete wall)after the recovery of 3503 working faces under the two conditions of uncut and cut top is compared and analyzed by flac~3DD software.The distribution of stress,deformation and plastic zone in the surrounding rock of the tunnel after heading in the return lane of 3505 working face,through the simulation results,is carried out.Analysis and comparison verify the feasibility of roof cutting and pressure relief Lane protection technology.(3)The design of the cutting and pressure relief alley:through the design and the practice of the cutting and pressure unloading engineering in the 3503working face,the later observation shows that the purpose of the pressure relief alley is achieved.