基于围岩受力影响的小净距隧道开挖方法优化

为了确定某小净距隧道适宜的开挖方法,利用有限元软件对全断面法、台阶法和单侧壁导坑法进行模拟,分析不同开挖方法引起的围岩应力云图,并重点对不同的开挖方法引起先行洞围岩及中夹岩柱的受力变化进行对比。结果表明:隧道开挖后在两洞仰拱部位出现拉应力集中区,两隧道之间最近的中夹岩柱是受力最为显著的部位,不同的开挖方法在周边围岩中产生的应力大小及变化趋势也存在差异,全断面开挖方法对先行洞周边围岩影响较小,台阶法的施工在两洞之间引起的应力较小。由此确定该小净距隧道先行洞采用全断面法,后洞采用台阶法进行开挖,通过现场实施,证明方法可行。

Optimization of Excavation Method of Small Spacing Tunnel Based on the Influence of Surrounding Rock Stress

In order to find the suitable excavation method of a small spacing tunnel, the full section method, the bench cut method and the unilateral pilot tunnel method are simulated with finite element software. the stress cloud map of surrounding rock caused by different excavation methods is analyzed, and the stress change of the following tunnel excavation on the first tunnel and the middle rock pillars is compared emphatically. The results show that the tensile stress concentration zone appears in the tunnel arch area after excavation, and the nearest middle rock pillar between the two tunnels is the most significant part of the stress, and the stress value and change trend of different excavation methods in the surrounding rock are also not the same, the full section excavation method has little influence on the surrounding rock around the leading hole, The construction of bench cut method causes less stress value between the two holes. It is determined that the small spacing tunnel first hole adopts the full section method, and the posterior tunnel is excavated by bench cut method, and the method is proved to be feasible by field implementation.