Rapid Receiving Technology of Shield Tunneling in Weak and Rich Water Strata in Dianchi Lake Area
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.
weak and rich water strataopening chiselingground groutingquick reception
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