黄土隧道施工方案的数值分析

黄土隧道围岩不同开挖与支护施工方案的数值分析，对了解黄土隧洞变形破坏机理以及黄土隧洞设计施工理论具有重要意义。对黄土隧道围岩采用中壁法和双侧壁导坑法开挖各3种不同支护顺序分别进行了模拟计算，考察了各个施工工序地表最大沉降量、隧洞拱顶最大下沉量、围岩塑性区分布、衬砌单元弯矩以及岩体总应变能变化。计算结果表明，从开挖方法来说，双侧壁导坑法要优于中壁法；从支护顺序来说，滞后支护要优于及时支护。此结果可为黄土隧道工程设计施工提供参考。

Numerical analysis of construction scheme of loess tunnel

The variations of five mechanical conditions such as the surface settlements, the displacement at vault of tunnels, the distribution of plastic zone of surrounding loess, the moment distribution of lining element and the total strain energy of surrounding loess are studied under three kinds of lining procedure with two different tunnel constructions, which is sequential excavation with a central heading and with a lateral heading. The results show that the sequential excavation with a lateral heading, which can decrease the amount of displacement at the vault of tunnels and of the maximal surface settlement and of the plastic zone of surrounding loess, is more preferable than that with a central heading. The tunnel lining in delayed construction compared with that in immediate construction is more favorable to enhance the stability of loess tunnel. It is shown that the analytical results are helpful for the design and construction of loess tunnels.