大断面黄土隧道CRD法优化研究

Study on Optimization of CRD Method for Large Section Loess Tunnel

为了确定安全合理的CRD法开挖方法,采用有限元分析软件对王家沟黄土隧道施工中CRD开挖法的开挖顺序、临时支撑形式、下台阶台阶长度进行数值模拟研究.通过对隧道变形情况、初期支护的受力情况对比分析表明:CRD法的开挖顺序为1234、临时支撑为曲线即拱形临时支撑、台阶长度为4 m时在控制围岩变形方面是有利的,部分钢拱架和锁脚锚管的轴向应力有所增大,但是增大幅度不大.

In order to identify safe and favorable excavation method in CRD method, the finite element software was applied to simulate the excavation sequence, the temporary support style and the different step length of low- er bench in Wang Jiagou loess tunnel excavation. The deformation and actual stress state of the support was com- paratively analyzed. The results show that the most favorable excavation sequence is ①②③④, the most stable style of temporary support is arch structure and the optimal step length of lower bench is 4 m in CRD method. The results also show that the axial stress of steel arch and locking tremies increase by a small margin.