大断面浅埋黄土隧道施工参数研究

针对大西客专某大断面浅埋黄土隧道,基于有限元Plaxis-3D分析软件,采用莫尔-库伦模型,对隧道三台阶七步开挖工法进行了施工参数数值模拟。研究了隧道开挖中不同开挖循环进尺、不同台阶长度、不同分块大小施工对隧道变形及稳定性影响。研究结果显示：开挖循环进尺为1 m时,开挖步最大累积变形为30 mm;台阶长度为5 m时,隧道相对收敛为74 mm;上台阶高度为3 m时,隧道相对收敛为76 mm。此开挖参数可以有效地控制隧道变形,保证隧道围岩稳定。

Study on Construction Parameters of Shallow and Large-section Loess Tunnel

Aiming at a shallow and large-section loess tunnel of Datong-Xi’an railway and based on Plaxis-3D finite analysis software, this paper uses Mohr-Coulomb model to numerically simulate the three-bench seven-step excavation method. The influence of different excavation footage cycles, lengths of step and sizes of block on the deformation and stability are studied. The results show as follows：when the excavation footage cycle is 1 m, the maximum accumulated incremental deformation of excavation step is separately 30 mm;when the length of step is 5 m, the relative convergence of tunnel is 74mm;when the length of upper step is 3 m, the relative convergence of tunnel is 76 mm. It finds out that the construction parameters above during excavation may make the deformation small with good stability.