纸坊隧道三台阶与两台阶开挖数值模拟对比分析

Comparative Analysis on Numerical Simulations of Three-bench Excavation Method and Two-bench Excavation Method:Case Study on Zhifang Tunnel

采用有限元分析软件对炭质板岩的纸坊隧道施工中的三台阶七步开挖法与两台阶五步开挖法进行数值模拟研究,分析2种工法的隧道变形情况、初期支护及二次衬砌的受力情况。分析结果表明:两台阶五步开挖法较三台阶七步开挖法,在控制变形方面是有利的,但是除锚杆内力有所减小外,钢拱架轴力、拱腰及侧墙部位初期支护喷混凝土、二次衬砌均有增大趋势。

Numerical simulation is made for the three-bench seven-step excavation method and two-bench five-step excavation method adopted in the construction of Zhifang tunnel located in carbonaceous slate ground. The deformation of the tunnel and the stresses acting on the primary reinforcement structure and the secondary lining under the condition of the above two excavation methods are analyzed. The analysis indicates that two-bench five-step excavation method is superior to three-bench seven-step excavation method in aspect of deformation control ; however, under the condition of two-bench five-step excavation method, the axial forces of the steel ribs and the stresses on the primary shotcrete and the secondary lining at the arch lumbar and the side wall have increasing tendency, except the fact that the axial forces of the bolts reduce.