超前锚杆加固机理的研究
Exploring Advanced Bolt Reinforcement Mechanisms

超前锚杆加固效果的准确评估及其合理的参数设计均依赖于对其加固机理的正确认识。为了说明土体与锚杆各项参数对锚杆加固效果的影响，建立锚杆-土体相互作用模型，以掌子面超前核心土挤出变形为参量，分别对锚杆与土体共同变形和出现滑移两种不同情况下锚杆的加固机理进行分析；针对锚杆与土体共同变形的情况提出加固系数k来计算锚杆加固效果，分析各项参数对加固效果的影响。最后利用计算机模拟的方式对超前锚杆的加固效果进行分析。研究结果表明：利用加固系数k可以有效分析锚杆、土体各参数对加固效果的影响；验证了锚杆锚固段长度的确存在极限值；并进一步说明了锚杆锚固段与拉拔段不同加固机理。研究结果对超前锚杆加固效果评估及其参数设计具有一定指导意义。
The accurate and reasonable evaluation of an advanced bolt's reinforcement effect and its parameter design depend on correct understanding of reinforcement mechanisms. In order to explain the influence of parameters of soil and bolt on the reinforcement effect, the bolt-soil interactional model was built. The reinforcement mechanisms of advanced bolts were analyzed with the extrusion deformation of the tunnel core soil under the condition whether the advanced bolt and the tunnel core soil have common deformation or not. The reinforcement factor k was introduced to calculate the reinforcement effect of bolts and analyzed the influence of parameters for reinforcement effect in the condition that bolt and soil had common deformation. Finally, the reinforcement effect of the advanced bolt was analyzed through computer simulation. The simulation results show that the influence of soil and bolt's parameters on reinforcement effect can be analyzed with the reinforcement factor k. The conclusion that the length of an anchor has its limit is verified. Furthermore, the different reinforcement mechanisms of anchorage section and drawing section were explained. These results provide significant guidance for reinforcement effect evaluation and parameter design of an advanced bolt