滇池区域软弱富水地层盾构快速出洞技术研究

Rapid Receiving Technology of Shield Tunneling in Weak and Rich Water Strata in Dianchi Lake Area

在昆明轨道交通五号线全线盾构施工过程中,由于存在的软弱富水地层为湖泊沉积地层,包含泥炭质土层、黏土、粉土、粉砂等多种地层,地下水位高,含水量大,出洞后洞门涌泥涌砂无法迅速封堵,上部地面塌方、端头沉降严重,全线多次进行盾构始发接收端头涌泥涌砂抢险施工。该地层盾构接收按常规洞门凿除+盾构接收+洞门封堵需10~15 d时间,存在施工过程长、风险难以掌控等问题[1]。针对富水地层盾构接收风险大问题,提出利用洞门结构上方缺口配合盾构掘进增加洞门结构裂缝从而快速凿除洞门+盾构到达洞门位置进行地面注浆封堵初步流水通道+盾构出洞后快速封堵洞门综合工艺措施,从而实现盾构安全快速出洞。实践结果表明,昆明轨道交通五号线土建六标在左线青少年宫站接收过程中,配合盾构稳定接收技术,从洞门凿除到盾构接收完全封堵洞门仅用72 h,在富水地层施工极大提高了施工效率及安全性。

During the shield tunneling construction process of Kunming Rail Transit Line 5,due to the presence of weak and water rich strata,which are lake sedimentary strata,including peaty soil layers,clay,silt,silty sand and other strata,the groundwater level is high and the water content is large.After exiting the tunnel,the mud and sand surge at the tunnel entrance cannot be quickly blocked,the upper ground collapses,and the end settlement is severe.The entire line has been carried out multiple emergency operations for the mud and sand surge at the starting and receiving ends of the shield tunneling.In this stratum,the shield tunneling reception process follows the conventional excavation of the tunnel entrance+shield tunneling reception+tunnel door sealing,which takes 10-15 days.There are problems such as long construction process and difficult risk control.A comprehensive method is proposed to address the high risk of shield tunneling in water rich strata,which involves quickly removing cracks in the tunnel portal structure by chiseling the opening above the tunnel portal structure and cooperating with shield tunneling.Additionally,a preliminary water flow channel is blocked by ground grouting technology when the shield machine reaches the tunnel portal position,and the tunnel portal is quickly blocked after the shield machine exits the tunnel,thereby achieving safe and rapid exit of the tunnel.Practical results showed that during the reception process of the sixth section of the civil engineering of Kunming Rail Transit Line 5 at the Youth Palace Station on the left line,combined with shield stable reception technology,it only took 72 hours from the excavation of the tunnel door to the complete sealing of the tunnel door by shield reception.This greatly improved the construction efficiency and safety in the construction of water rich strata.