考虑剪胀与中间主应力的被锚巷道围岩稳定性分析

Analysis of surrounding rock stability of bolted roadway considering dilatancy and intermediate principal stress

为研究被锚巷道围岩稳定性,将锚杆的支护作用考虑成作用于锚固体两侧的一组夹紧力与强化了锚固体强度参数,综合考虑围岩剪胀特性与中间主应力效应,建立被锚圆巷弹塑性力学模型,推导出围岩的应力场与位移场解析解,求得围岩塑性区半径表达式。算例研究表明:随着中间主应力系数增大,塑性区半径、洞壁位移与锚杆轴力均减小,最大主应力峰值增大;随着剪胀角增大,塑性区半径稍有减小,最大主应力峰值稍有增大,洞壁位移与锚杆轴力急剧增大;影响因素最不利组合(b=0,ψ=30°)与影响因素最有利组合(b=1,ψ=0°)相比,塑性区半径增大了23.49%,最大主应力峰值变化很小,洞壁位移增大了76.20%,锚杆轴力增大了1.94倍。该结果在围岩稳定分析方面具有一定工程实用价值,也可为锚杆支护设计和优化提供一定理论基础。

To study the surrounding rock stability of bolted roadway, the supporting effect of the bolt is considered as a set of clamping forces acting on both sides of the anchor bolt, and the strength parameters of the anchor bolt are strengthened. With the dilatancy characteristics and intermediate principal stress effects of the surrounding rock comprehensively considered, an elasto-plastic mechanical model of the bolted circular roadway is established, and the analytical solutions to the stress field and displacement field of the surrounding rock are derived, and the expression of the radius of the surrounding rock plastic zone is obtained. The results have shown that with the increase of the intermediate principal stress coefficient, the radius of the plastic zone, the displacement of the cave wall and the axial force of the bolt all decrease, but the peak value of the maximum principal stress increases. As the dilatancy angle increases, the radius of the plastic zone decreases slightly and the peak value of the maximum principal stress increases slightly, but the displacement of the roadway cavern wall and the axial force of the bolt increase sharply. With the most unfavorable combination of the impact factors(b=1, ψ=0°) compared against the most favorable combination of the impact factors(b=0, ψ=30°), the radius of the plastic zone increases by 23.49%, the peak of maximum principal stress changes slightly, the wall displacement increases by 76.20%, and the axial force of the bolt increases by 1.94 times. The results have certain engineering practical value in the stability analysis of the surrounding rock, and also provide certain theoretical basis for the design and optimization of bolt support.