富水粉细砂岩隧道涌水涌砂处理技术研究

第三系富水粉细砂岩层隧道地层含水量高,开挖后稳定性极差,极易发生围岩变形、坍塌、流砂,施工难度大,安全风险高。本文以兰渝铁路马家坡隧道为背景,以隧道涌水涌砂事件为切入点,分析了富水粉细砂岩涌水涌砂原因,提出了"抽排水+注浆加固+六部CRD开挖+加强初支+综合降水"相结合的施工方案,即采用后退式分段注浆加固和六部CRD开挖施工工艺,并通过加强初期支护,轻型井点降水+深井真空降水,有效解决了隧道涌水涌砂问题,保证了施工顺利进展。

Research on Water and Sand Gushing Treatment Technology of the Tunnel in Water-rich Fine Siltstone

The water content of the tunnel in the Tertiary water-rich fine siltstone is high,which leads to poor stability after excavation,and easy to occur surrounding rock deformation,collapse and quicksand,resulting in great difficulty in construction and high safety risk.With the background of Majiapo Tunnel of Lanzhou-Chongqing railway,this paper analyzes the causes of water and sand gushing in water-rich fine siltstone starting from the water and sand gushing event of the tunnel,and puts forward the construction scheme of "drainage+grouting reinforcement+six-step CRD excavation+strengthening the initial support+comprehensive dewatering",that is,adopting the construction technology of retreating sectional grouting reinforcement and six-step CRD excavation,the problem of water and sand gushing in tunnel is effectively solved by strengthening the initial support and light well point dewatering+deep well vacuum dewatering,and the smooth progress of construction is ensured.