Stability criterion and control technology of roadway surrounding rock in Thick coal seam with multi-layer gangue...

The stability criteria for surrounding rock in thick coal seam with multi-layer gangue roof are crucial theoretical foundations for assessing the risk of roof collapse in mine roadways. This study focuses on the deformation characteristics of surrounding rock in the thick coal seam with multi-layer gangue roof at the Tashan Mine, establishing a solid-supported beam mechanical model for the coal-rock layer combination. The mechanical criteria for shear failure of roof anchor cables and roof delamination are derived. Additionally, this paper employs 3DEC numerical simulations to investigate the distribution patterns of the plastic zone, stress field, and displacement field under varying lateral pressure coefficients.The research results show that the initial position of the plastic zone development of the roadway roof in the thick coal seam with gangue roof is the gangue layer of the roof, and further extension causes the failure of the supporting components until the instability of the roadway. When the lateral pressure coefficient λ > 1.2, delamination occurs in the shallow gangue layer of the roadway roof, resulting in a loss of load-bearing capacity. As the depth of the roof increases, the influence of the deep gangue layer on roof delamination gradually diminishes. Based on the engineering background of 5110 roadway in Tashan Mine, the control technology of ' roof bolting and grouting + grading support + anchor cable truss ( roof and sidewall ) ' is put forward. After the optimization scheme is adopted, the maximum deformation of roof is 178 mm, which is 61% lower than that of the original support, and the maximum separation amount is 92 mm. The bonding of the slurry with the roof strata forms a composite structure, enhancing the integrity of the surrounding rock and yielding favorable results in engineering applications.