风化花岗岩隧道矿山法施工地下水渗流特征与防水技术研究

Groundwater Seepage Characteristics and Waterproof Technology in Weathered Granite Tunnel under Mining Method Construction

以风化花岗岩隧道为工程背景,通过现场监测和数值模拟研究手段,研究了风化花岗岩隧道所处地层在矿山法施工条件下地下水的渗流规律,并通过不同防水结构下流固耦合特征的分析,探讨了不同防水结构下地下水对二次衬砌的影响,进而在考虑场区地下水环境变化的基础上,提出了合适的防水控制措施。结果表明:隧道全断面开挖时,地下水流速在仰拱上部断面支护之后达到最大,地下水流速最大值位于拱脚处,随后依次降低;隧道开挖后,地下水水位迅速下降,在仰拱支护期间达到最低点,此后缓慢恢复;地铁隧道矿山法施工防水结构大致简化为全包防水型和控制性全包防水型,隧道下部结构对防水结构型式的变化较敏感,不同防水结构下隧道断面处二次衬砌背后孔隙水压力分布有很大的差异;隧道拱顶处地下水水头越高,排水盲管的铺设对隧道下部结构孔隙水压力的折减效果越显著;全包防水结构下隧道下半部分孔隙水压力的平均值较大,控制性全包防水结构下隧道上半部分孔隙水压力的平均值较大。

Based on the engineering background of weathered granite tunnel,through field monitoring and numerical simulation,this paper studies the characteristics of groundwater seepage around weathered granite tunnel constructed by the mining method,and conducts fluid-solid coupling analysis under different waterproof structures to obtain the impact of groundwater on the secondary lining.Furthermore,considering the changes of the groundwater environment,the paper proposes appropriate safety waterproof control measures.The results show that during full-face tunnel excavation,the groundwater flow velocity reaches the maximum after the support of the upper section of the inverted arch,and the maximum value is located at the arch foot,and then decreases.The groundwater level drops rapidly after tunnel excavation,and reaches the lowest point during inverted arch support,and then recovers slowly.The waterproof structure of the subway tunnel constructed by the mining method is roughly simplified as fully wrapped waterproof type and controlling fully wrapped waterproof type.The structure of the lower tunnel is sensitive to the change of waterproof structure type,and the distributions of pore water pressure in the tunnel section behind two liners under different waterproof structures are very different.The higher the groundwater head at the tunnel vault,the more remarkable the effect of drainage blind pipe laying on reduction of the pore water pressure at the substructure of the tunnel.The average pore pressure in the lower half of the tunnel is larger than that in the upper half under fully wrapped waterproof structure.However,the average pore pressure in the upper half of the tunnel is larger than that in the lower half under controlling fully wrapped waterproof structure.