单拱4车道浅埋偏压隧道锚杆支护参数优化研究

Optimization of rock bolts supporting parameters for single arch shallow tunnels with four traffic lanes under unsymmetrical loads

锚杆参数优化能提高隧道围岩稳定性,节省隧道建设成本.运用数值计算方法对锚杆支护形式和参数进行优化分析是一种十分有效的方法.针对单拱4车道公路隧道断面大的情况,考虑了隧道处于浅埋偏压的地质条件,采用双侧壁导坑法开挖,对隧道的初期支护进行了优化分析.在不同锚杆横向间距与纵向间距比值条件下,研究地表沉降、拱顶沉降、墙腰收敛值的变化规律,为单拱4车道公路隧道提供优化的锚杆支护方案.结果显示,当锚杆的横向间距与纵向间距比值接近于1时,能够更有效的控制围岩的变形.

Optimization of rock bolts supporting parameters can improve the stability of surrounding rocks, and save the cost of tunnel construction. Rock bolts supporting layouts and supporting parameters are optimized by numeric simulation and the result proves the method is valid. Considering the geological properties of shallow and large cross section tunnels, the method of double side excavation is adopted for the tunnel primary support numerical simulation. The optimization analysis of supporting parameter is carried out. Under different ratio of circumferential space to longitudinal space, different curves of ground settlement, crown settlement and the sidewall convergent displacement are presented, and the most reasonable rock bolt layout style is given from the analysis of variety ratios. According to the result, when the ratio of circumferential space to longitudinal space is approximately equal to 1, the rock bolts can more efficiently make control of the surrounding rock.