深埋分区破裂隧道锚杆支护力学机制

Rock bolt support mechanism of deep buried zonal disintegration tunnel

为深入研究深埋分区破裂隧道锚杆支护的力学机制,首先通过对实际工程测试结果和模型试验测试结果进行对比分析,得出分区破裂现象的产生主要是由于深埋隧洞在较大轴向应力作用下,围岩应变域出现拉压交替所致,而锚杆支护可有效降低围岩的此破坏现象;在此基础上,通过建立锚杆与围岩相互作用力学模型,得到了锚杆轴向应力和界面摩阻力的分布特征:即锚杆的轴向应力在劈裂环达到峰值,沿锚杆走向形成多个峰值;锚杆界面摩阻力则会在锚杆锚头一定范围内形成拉应力,在锚杆杆尾一定范围形成压应力.因此,锚杆支护的支护机理为锚杆锚头在围岩深部压力(压应变)区域与围岩的相互作用呈现嵌入与咬合的锁定作用,锚杆杆尾与围岩的相互作用则呈现悬吊作用,由此锚杆与支护围岩形成一个比较稳定的自承拱,起到支撑作用.自承拱的出现,使锚杆和岩体受到了挤压作用.因此。

In order to further study the bolt supporting mechanism of the deep zonal disintegration tunnel, this paper obtained the conclusion that the rock bolt can effectively reduce or eliminate the phenomenon of zonal disintegration based on the analysis of the in-site engineering test results and the model test results. The zonal disintegration is mainly due to the larger axial stress to the surrounding rock of the deep tunnel lead to the alternately emergence of the tensile and compressive strain field. The interaction mechanism model is established Through the model, the axial stress distribution was obtained which have several stress peak along the rock bolt axial direction, but the shear stress will be formed tensile stress distribution form within a certain range of rock bolt head, and the friction stress will be formed compressive stress distribution form within a certain range of rock bolt tail. Therefore, the rock bolt mechanism is that the interaction of anchor head and compressive stress range rock mass lead to lock and embedded action, and the interaction of anchor tail and tensile stress range rock mass lead to suspended action. The rock bolt and support rock mass should form a relatively stable self-supporting arch to support the surrounding rock. The occurrence of self-supporting arch result in the extrusion action between the rock bolt and the rock mass. Therefore, the acting mechanism of rock bolt is embedded-locked-tensile-self-supporting-arch-support-extrusion.