pilot tunnel

During the construction, we use the excavation method of first excavating pilot tunnel and the top layer 、 middle layer and the bottom layer parallel fly-over crossing.

在工程施工中采用导洞先行，顶层、中层、底层平行立体交叉的开挖方案。

Three-dimensional numerical analysis method was used to study the characteristics of deformation and stress of surrounding rock and supporting structure on the process of tunnel unkennel construction. The comparative analysis of three-steps-seven-footwork tunnelling method and small pilot tunnel method were performed. 3.

采用三维数值分析手段研究隧道出洞施工过程中的围岩与支护结构变形受力特点，分别对三台阶七步法和超前小导洞法两种出洞施工方案进行对比分析。

Further, the optimum excavation subsequence is gain through calculating onside wall pilot tunnel plan by finite element method program and do the sensitivity analysis of soil parameter for affects on excavates.

又对侧壁导坑施工方案进行进一步有限元仿真模拟计算，研究得出最优的块体开挖顺序，并作了开挖土体参数对开挖影响的敏感性分析。