不同锚固长度下巷道锚杆力学效应分析及应用

为研究不同锚固长度对巷道围岩的控制效果，从理论方面推导了锚杆应力分布规律，建立了不同锚固长度下巷道围岩力学分析模型，考虑分析了锚杆直径、围岩强度参数、锚固长度、预紧力、布设间距等影响因素，给出了巷道锚杆支护设计的工程建议措施，并通过开展现场试验验证了本文理论研究成果的正确性。研究表明：锚杆受力主要集中在锚固段端头1/3范围内，且沿长度方向杆体剪应力与轴力不断递减；在软岩中更利于锚杆锚固作用的发挥；施加高预紧力，并留设一定的自由段长度，有利于锚杆预紧力在围岩中扩散，可形成有效的锚固围岩承载结构，充分发挥杆体支护潜力；当锚杆布设间距较大时，可通过提高预紧力、适当减少锚固长度来增加预紧力对围岩的控制效果。

Mechanical effect analysis of bolts in roadway under different anchoring lengths and its application

In order to study the control effect of different anchoring lengths on surrounding rock in roadways，the stress distribution laws of bolt were deduced，and the mechanical analysis model concerning different anchoring lengths was established through theoretical method.Different factors，such as bolt diameter，surrounding rock strength，anchorage length，pre-tightening force，bolt spacing，etc.，were analyzed，engineering measures on bolt designing were also recommended，and the correctness of theoretical results was verified through filed test.The results show that the inner force of rock bolt concentrates in the 1/3 range of anchoring section mainly，and damps to the root along the length of bolt.In softer rock mass，anchorage effect is better to be exerted.Adopting high pre-tightening force and setting a certain length of free-segment can help pre-tightening force to spread in surrounding rock，form effective bearing structure in anchored rock mass，and achieve a supporting potential of bolt.When bolt spacing increases，a better control effect of surrounding rock can be achieved through applying high pre-tightening force and reducing anchorage length appropriately.