大相岭隧道富水断层区段极易引起突水、突泥现象,具有很大施工风险,高位排水能够有效降低掌子面前方高水压力积聚程度。基于现场实测和动态流-固耦合数值力学方法,研究不同水位条件下高位排水工法与隧道稳定性之间关系,提出最优高位排水管分布方案。研究得出:大相岭隧道F6断层水压最高达到1.98 MPa,排水后可实现安全施工,衬砌背后水压降低至10 m左右,因此,防涌突水主要集中在掌子面开挖期;拱顶排水管排水量最大,越靠近拱脚的位置排水能力越差,从拱顶到拱脚呈下降趋势,应使拱顶附近排水管密度大于拱脚附近;实际施工中为更快达到均匀降水效果,应先对拱顶部位打设排水管,后对拱脚部位打设排水管;研究了排水管根数、排水量及掌子面挤出变形相互关系,从经济性和疏水加固效果出发,提出了排水管合理布置方法及建议参数,对富水断层隧道掌子面防突与塌方及运营隧道结构设计具有重要参考价值。
The construction of Daxiang mountain tunnel in water-rich fault has great risks of causing water bursting and mud gushing easily.High-position drainage can reduce water pressure ahead of working face effectively.By using field test and numerical simulation,under different water-level conditions,the interrelation between method of high-position drainage and stability of tunnel is studied;and the optimal plan of arrangement of high-position drainage pipes is put forward.Studies show that: maximum water pressure of Daxiang mountain tunnel in fault is up to 1.98 MPa.The tunnel can be constructed securely after drainage and the maximum water head is only 10 meters.Therefore,prevention of water bursting is mainly concentrated in the period of tunnel face excavation.The drain volume of drain pipes at vault is maximum.The closer drain pipes and arch foot are,the more poor drainage capacity is;and the density of drain pipes at vault should be higher than that at arch foot.In actual construction,for faster to reach drain effect,drain pipes at vault should be first to arranged,then at arch foot.Interrelation between number of drain pipes,drain volume and extrusion deformation of tunnel face is studied.According to economy and effect of hydrophobic reinforcement,reasonable drainage scheme is put forward.