藏噶隧道穿越冰水沉积层围岩加固与掘进技术

藏噶隧道穿越长915 m冰水沉积层,土石粒径大小不均,孔隙率大,自稳性差,受地下水影响大,因此采取有效的地层加固止水措施极为必要。基于冰水沉积层地层特性和穿越该地层隧道施工风险分析,提出富水季节和枯水季节先分别采用“帷幕注浆+管棚+小导管”和“管棚+小导管”对围岩注浆加固,然后采用小断面三台阶开挖的施工方案。经实施隧道顺利穿越长距离冰水沉积层,达到了安全高效的目标。

Reinforcement and Driving Technology for Surrounding Rock of Zangga Tunnel in the Glaciofluvial Deposit

The Zangga tunnel passes through glaciofluvial deposit,the length of which is 915 m.The size of earth-rock particle is uneven,the porosity is large,the self-stability is poor,and it is greatly affected by groundwater.Therefore,it is necessary to take effective measures of reinforcement and water plugging in the stratum.Based on the formation characteristics of the glaciofluvial deposit and the risk analysis of the tunnel construction crossing the stratum,it is proposed that curtain grouting+pipe shed+small conduit and pipe shed+small conduit should be used to grouting reinforcement for surrounding rock in the rich water season and the dry water season respectively.Then the construction scheme of small section and three bench excavation was adopted.After implementation,the tunnel passed through the long-distance glaciofluvial deposit and the goal of safety and efficiency was achieved.