Abstract:

No. 3 Line of Wuhan Metro is the first Metro tunnel crossing Hanjiang River in China. Due to the complex geological conditions of the project, “mining method + shield method” are adopted for the tunnel. The effect of the tunnel support installed in mining method has fundamental influence on the successful passing of the shield. In the paper, the parameters of the primary support, including anchor bolt length, anchor bolt row spacing and shotcrete grade, are optimized by means of FLAC 3D calculation and orthogonal experiment, so as to minimize the construction risks and to reduce the construction cost. The results show that: 1) The optimization design by introducing the orthogonal experiment method to the numerical simulation is feasible and convenient, which can reduce the experiment times significantly; 2) The rules of the influence of the support parameters on the tunnel deformation and construction cost are obtained, and the optimum support parameters are determined; 3) The feasibility of the optimum support parameters is verified. The paper can provide theoretical and practical reference for similar projects in the future.

Key words: Metro tunnel, orthogonal experiment, primary support, numerical simulation, optimization