山岭隧道断层破碎带富水段开挖方法的对比分析

以小北山1号隧道为研究对象,采用FLAC3D有限元模拟分部开挖的几种工法,对隧道穿越F3断层破碎带处的开挖过程进行了模拟。针对4种不同施工工法情况下竖向位移、围岩应力以及塑性区进行了对比分析,结果表明,采用预留核心土法时得到的底部隆起、拱顶沉降量和拱脚最大主应力是四种工法中最小的;尽量减小对围岩体的扰动可以对隧道顶部的沉降控制起到一定的作用;拱肩处出现的受拉塑性区在施工过程中容易造成洞室的整体失稳,需及时支护。

Comparison Analysis on Excavation Method for Water-rich Section in Fault Fractured Zone of Mountain Tunnel

Taking Xiaobeishan No.1 Tunnel as the research object,the excavation process of the tunnel passing through F3 fault fracture zone has been simulated by using FLAC3D finite element method.The vertical displacement,surrounding rock stress and plastic zone under four different construction methods have been compared and analyzed.The results have shown that for the bottom uplift and vault settlement obtained by using reserved core soil method,the reduction and maximum principal stress of arch foot are the smallest among the four construction methods.Minimizing disturbance to surrounding rock mass could play a role in controlling the settlement of the tunnel top.The tension plastic zone at the arch shoulder is easy to cause the overall instability of the tunnel in the construction process,so timely support is needed.