非连续结构面对巷道顶板稳定性及锚杆支护作用的影响机制研究OA

The stability of roadway roof is one of the key factors affecting safety and production in coal mines,yet the presence of discontinuous structural planes(DSPs)has a considerable impact on roof stability and support effectiveness.This study investigated the effects of four different types of DSPs on the deformation and failure of roof,the force distribution of rock bolts,and the evolution of force chain based on physical model experiments and UDEC numerical simulations on roadway roof.The main conclusions are as follows:The physical and numerical models of the roof under four different DSP conditions exhibit arching failure characteristics.A pressure arch determination method based on numerical simulation was proposed,and the evolution mechanism whereby both the height and angle of the pressure arch enlarge as the DSP develops increases was uncovered.Besides,the regional force distribution characteristics were clarified,that is,the force on the bolts at the roof corners is much higher than that at the central position.It was found that with the development of DSP,the initial stress increase in rock bolts diminishes during early deformation of surrounding rock,while stress attenuation intensifies during severe deformation.The weakening effect of DSP on surrounding rock force chains was revealed.Such a weakening effect leads to reduced stability and expanded extent of unstable surrounding rock,which drives the pressure arch evolution from low to high.The negative correlation between the development degree of DSP and the effectiveness of rock bolt support was explained.To be specific,a higher development degree of DSP corresponds to more pronounced rock bolt anchoring failure and gradually decreasing effectiveness in restraining rock deformation through increased support resistance.The increase in DSP not only significantly weakens the integrity and strength of the roof surrounding rock and exacerbates rock deformation and failure,but also makes the rock bolt more prone to debonding failure and worsens overall rock bolt support performance.