新城金矿某中段巷道加锚围岩损伤失效与锚固时机数值模拟研究

    Numerical simulation of damage failure and supporting time of anchored surrounding rock in a middle roadway of Xincheng Gold Mine

    • 摘要: 锚固时机的合理选择应在充分发挥支护结构对围岩控制作用的同时,也能积极调动围岩的自稳能力,合理的锚固时机对保证掘进工程的安全性与经济性具有重要意义。本文通过综合考虑围岩弹性损伤模型、锚杆弹塑性硬化模型和界面双指数剪切滑移模型,建立加锚围岩损伤与锚固失效的数值模拟方法,并以新城金矿某中段大巷的掘进与支护工程为例,对比分析不同支护时机与不同锚固长度条件下巷道收敛变形、围岩损伤与锚杆状态,发现锚固锚杆支护越早,巷道收敛变形越小,但是过早的支护时机将使得更多的锚固锚杆进入塑性硬化与锚固界面滑移失稳阶段而发生锚固失效;由于新城金矿高围岩强度限制了围岩损伤演化与变形发展,支护时机和锚固长度对巷道收敛变形和开挖损伤区大小影响也较小;通过对围岩及锚固锚杆力学响应的分析,发现锚固长度为1.7 m时,锚固锚杆发生滑移脱黏现象更少,并确定了离掌子面距离为4 m进行锚固锚杆支护为最佳支护时机。该研究为其他矿山掘进与支护工程支护时机研究提供了理论分析方法。

       

      Abstract: The reasonable choice of supporting time should not only fully develop the control of supporting structure on surrounding rock, but also actively mobilize the self-stability ability of surrounding rock. Rational supporting time is of great significance to guarantee the security and economy of excavation. In this paper, a numerical simulation method for the damage and failure of anchored surrounding rock is established by comprehensively considering the elastic damage model of surrounding rock, the elastoplastic hardening model of bolt and the double exponential shear-slip model of interface. Taking the excavation and support engineering of a middle roadway in Xincheng Gold Mine as an example, the convergence deformation of roadway, the damage of surrounding rock and the state of bolt under different supporting time and different anchored length are compared and analyzed. It is found that the earlier the anchoring bolt support is, the smaller the convergence deformation of roadway is, but the earlier the supporting time will make more anchoring bolts enter the stage of plastic hardening and slip instability of anchored interface, resulting in anchored failure. Because the high strength of surrounding rock in Xincheng Gold Mine limits the damage evolution and deformation development of surrounding rock, the supporting time and anchored length have little influence on the convergence deformation of roadway and the size of excavation damage zone. Through the analysis of the mechanical response of the surrounding rock and the anchoring bolt, which is found that when the anchored length is 1.7 m, the anchoring bolt has less slippage and debonding, and the distance from the palm surface is determined to be 4 m for the anchoring bolt support as the best supporting time. This investigation provides a theoretical analysis method for the study of supporting time of the excavation and support engineering in other mines.

       

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