Recently，The largest earth pressure balance shield machine in Beijing-Tianjin-Hebei region jointly built by China Railway Construction Heavy Industry and China Railway 12th Bureau“Xing'an”（Excavation diameter 12.72 meters）Help Tianjin to Beijing Daxing International Airport Railway Phase II Bid 1 Yu'an Tunnel 3 through。

Equipment exits the hole

It is reported that，The project is located in the alluvial plain of North China.，The shield tunneling section is mainly a long-distance silty clay stratum.，The minimum overburden thickness is less than 8m.，Among them, 1800 meters are located within the Yongding River.，Formation stability is poor、Groundwater is abundant，The project has a large excavation section.、The construction distance is long、Formation viscosity is strong、Gao Fu Shui、Shallow covering soil and the like.，Large earth pressure shield construction with large diameter is easy to cause large stratum disturbance.、Difficult control of soil chamber pressure and the like.，The construction is difficult。

Device origination

To overcome the above difficulties,，Railway Construction Heavy Industry Co., Ltd. and China Railway 12th Bureau Co., Ltd. carry out targeted design of equipment，The first slag tapping system of parallel double spiral machine in China has been developed.。Compared to single screw configuration，The parallel double-screw machine has the advantages of better maintaining the stability of the excavation face,、High accuracy of soil chamber pressure control、The construction is not delayed due to the maintenance of a single screw machine and the like.。At the same time, two screw machines discharge slag alternately.，It can effectively deal with the gushing problem of water-rich strata.，The continuity and safety of construction are guaranteed.。This configuration not only effectively reduces the risk of shield passing through risk sources and water-rich strata, but also effectively reduces the risk of shield passing through water-rich strata.，It also further improves the construction efficiency.。

The largest earth pressure balance shield machine in Beijing-Tianjin-Hebei region“Xing'an”Offline in Changsha Second Industrial Park of Railway Construction Heavy Industry

Since equipment mobilization，China Railway Construction Heavy Industry and China Railway 12th Bureau Group Co., Ltd.“High specification positioning、Start with high standards、High quality construction”Aim，For adjacent existing lines、Under the Yongding River、Tight construction period and so on.，Optimize the construction scheme，Formulate targeted measures，The safe crossing of the shield machine is realized.，The construction safety is effectively guaranteed.，And greatly improve that construction efficiency of the equipment.。The maximum daily footage of the equipment in the tunneling construction is 26 meters.，Maximum monthly footage 520m，Leading the industry。

Yu'an No.3 Tunnel is the key track-laying channel of the airport connecting line connected with Jinxing Railway.，It is also the only shield tunnel of Jinxing Railway.，“Xing'an”Smooth penetration of shield section，It has laid a solid foundation for the successful completion of the second phase of the railway project from Tianjin to Beijing Daxing International Airport.。