深埋巷道锚杆破断失效机理

Mechanism of bolt breaking in deep roadway

锚杆破断失效是深埋巷道支护面临的工程问题之一.采用现场调研、理论分析等方法,对深埋巷道锚杆破断失效形式、机理进行了分析.得到结论:1)深埋巷道锚杆破断失效形式主要有剪断失效、脆断失效、折断失效、拉断失效、崩盘失效和松脱失效;2)材料缺陷和受载性能是深埋巷道锚杆破断失效的内因,荷载超过极限荷载是深埋巷道锚杆破断失效的外因;3)拉伸、剪切、扭转等载荷复合作用下,锚杆有效直径减小,拉应力增大,导致破断失效;4)采用恒阻大变形锚杆或二次支护工艺,能够实现深埋巷道锚杆破断失效和围岩变形的协调控制.研究结果对深埋巷道围岩控制具有参考意义.

Bolt breaking is one of engineering problems of deep roadway support.The form and mechanism of bolt breaking was studied by using site investigation and theoretical analysis.Following results were obtained：1 ）The forms of bolt breaking in deep roadway are shear failure,brittle fracture failure,breaking failure,tensile failure,ejection failure and loosening failure;2）Material defect and bearing behavior are the intrinsic cause of bolt breaking in deep roadway,and the extrinsic cause lies in the overload,namely the load of bolt exceed its limit load;3）Under the combined effect of tensile load,shear load and torsion load,the effective diameter of the bolt decrease and the tensile stress in the bolt increase,as a result,the bolt is broken easily;4）Coordinated control of bolt breaking and surrounding rock deformation in deep roadway can be realized using constant resistance and large deformation anchor bolt or secondary support technology.The results provide a reference for surrounding rock control of deep roadway.