复杂地质条件下隧道开挖方式的选择和优化

Selection and Optimization of Tunnel Excavation Methods under Complex Geological Conditions

公路隧道施工中,复杂工程地质条件下隧道开挖方式的选择对隧道围岩稳定性、施工安全及保证施工进度起到确定性作用。为了优化梅花隧道开挖方式,本文采用MIDAS/GTS有限元软件对隧道开挖过程进行模拟计算,分析不同开挖方式下隧道围岩应力应变特征,结果表明:单侧壁导坑法对应的围岩应力最大,全断面开挖方法次之,上下台阶分步开挖方法对应的拱顶围岩应力最小;采用全断面开挖法、单侧壁导坑开挖法时,隧道拱顶区域会产生拉应力;采用全断面开挖法对应的高应力区位于与拱腰围岩开挖边界处,而采用上下台阶分步开挖法对应的拱腰围岩高应力区则离开挖边界有一定距离。

In the construction of highway tunnels,the selection of tunnel excavation methods under complex engineering geological conditions plays a deterministic role in the stability of the tunnel surrounding rock,construction safety and ensuring the construction progress.In order to optimize the excavation method of the Meihua tunnel,this paper uses MIDAS/GTS finite element software to simulate the tunnel excavation process and analyze the stress and strain characteristics of the tunnel surrounding rock under different excavation methods.The results show that the surrounding rock stress corresponding to the single-side pilot tunnel method is the largest,followed by the full-section excavation method,and the vault surrounding rock stress corresponding to the stepwise excavation method of the upper and lower steps is the smallest;when the full-face excavation method and the single-side pilot pit excavation method are used,tensile stress will be generated in the tunnel vault area;the high-stress area corresponding to the full-face excavation method is located at the boundary of the excavation of the arch waist surrounding rock,while the high-stress area of the arch waist surrounding rock corresponding to the stepwise excavation of the upper and lower benches is a certain distance away from the excavation boundary.