Research On Failure Characteristics And Control Technology Of Roadway Surrounding Rock Affected By Secondary Mining

Aiming at the serious problem of surrounding rock deformation of 3309 transportation lane in Sangshuping No.2 well in Hancheng mining area,a combination of theoretical analysis,numerical simulation,and on-site measurement is used to affect the stress distribution and plasticity of surrounding rock in 3309 transportation lane caused by the mining of 3308 working face.The damage scope was comprehensively studied and the surrounding rock control plan was put forward for field application.The main conclusions are as follows:(1)Based on the limit equilibrium theory,it is calculated that under the influence of another mining,the peak support pressure of coal pillars near the goaf is at 2.27m from the roadway surface,and the peak support stress of the coal pillar sill on the roadway side is at 2.04m from the roadway surface.In the second mining stage,the maximum force on the coal pillar ledge of the roadway is 19.27MPa.According to the empirical formula,the strength of the coal pillar is 14.3 MPa.The result shows that the serious deformation of the coal pillar of the roadway is mainly due to the excessive force of the coal pillar and insufficient bearing capacity.(2)Numerical simulation studies show that the maximum stress difference between the coal pillar and the coal wall of the roadway between 100m in front of the working face and 40m behind the working face exceeds 12.4MPa,and the plastic failure range differs by 1.0m.The deformation of the surrounding rock of the roadway is mainly caused by the roadway coal.It is caused by the destruction of the pillar and has the characteristics of dynamic change.The specific performance is:the stress distribution of the coal pillar after 40m in front of the working face shows an asymmetric bimodal distribution,and the peak position is within the range of 2?2.25m from the surface of the roadway,and the junction of the coal pillar and the roof of the roadway begins to plastically fail.Within 10m from the working face,entering the initial stage of influence of mining,the maximum stress of the coal pillar sill of 3309 roadway is 26MPa,and the peak value is 2.5-3.0m from the roadway surface.The plastic range at the bottom corner of the coal pillar has been significantly expanded.Within 10m behind the working face,the peak stress increase reached 40.7MPa,and the stress distribution changed from "double peak" to“single peak" distribution.The stress peak shifted from the edge of the coal pillar to the middle of the coal pillar.(3)Through the analysis of the stress distribution of the surrounding rock of the roadway under the influence of mining,the non-uniform deformation and failure characteristics of the two sides of the roadway were clarified,and the surrounding rock control plan of "cut roof pressure relief+reinforcement support" was proposed and field tests were carried out.The test results show that:? After adopting "cut roof pressure relief+reinforcement support",the coal pillar damage depth is concentrated in the range of 2m.? CoMPared with before the implementation of the control technology,the convergence of the roadway roof,coal pillar slab and coal wall slab has decreased by 50%,40%,and 47%respectively,which proves that the deformation of surrounding rock has been effectively controlled.The research can provide a basis for the deformation control and stability analysis of the surrounding rock of the mining roadway in Sangshuping No.2 Well,and it also has certain reference value for the research on the surrounding rock control technology of the roadway under similar conditions.