Overburden fracture and deformation patterns in gently inclined coal seam working faces under different fault blocks

GAO Zhihu; MU Guohu; GAO Wendong; NIU Shengli; WANG Junqi

doi:10.11799/ce202511018

Abstract：When mining in a gently inclined coal seam working face enters the fault influence zone,uneven stress distribution occurs on the supports,and severe deformation and failure of the surrounding rock in the roadways are observed.To systematically reveal the differential failure patterns of the overburden in this area,we take the 250602 working face of Zaoquan Coal Mine as an engineering case.Using a combined research approach of theoretical analysis,UDEC numerical simulation,and field measurement,and based on the spatial relationship between the working face and the fault,the overlying strata structure is simplified into three mechanical models:a beam fixed at both ends,a beam fixed at one end and simply supported at the other,and a cantilever beam.The analytical solutions for roof deflection in each model are derived based on the superposition principle,and a buckling check criterion is introduced to determine the roof buckling instability characteristics.On this basis,a comparative analysis is conducted using UDEC discrete element numerical simulation from the perspectives of development height of the"two zones"in the overburden,main roof subsidence,and failure morphology of the overburden,systematically revealing the evolution patterns of overburden failure in gently inclined coal seam working faces within the fault influence zone.The research results show that,when the working face is mined from the hanging wall side of the fault,the main roof subsidence significantly increases compared to normal mining,and the stratum caving morphology in the fault influence zone exhibits a"pile-up"pattern.When the working face is mined from the footwall side,the main roof subsidence further increases,and the fault zone exhibits overall sliding failure.Field borehole inspection test results of the roof are generally consistent with the numerical simulation results,verifying the reliability of the research methodology.