Recently，Large-diameter earth pressure balance shield machine jointly built by China Railway Construction Heavy Industry and China Railway 12th Bureau“Xing'an”It started smoothly in the section of Yu'an No.3 Tunnel of Jinxing Railway Phase II.，Start trial driving，It marks that the Jinxing Railway Project from Tianjin West Railway Station to Beijing Daxing International Airport Station, constructed by the 12th Bureau of China Railway, has formally entered a new stage of shield construction.，After completion, Tianjin and Beijing Daxing International Airport will be accessible in 30 minutes.。

“Xing'an”The shield machine starts

It is understood that，“Xing'an”Excavation diameter of shield machine 12.72 meters，Length of complete machine: 113m，The total weight is 2500 tons，The installed power is 4600 kilowatts，It is the largest diameter earth pressure balance shield machine used in Beijing-Tianjin-Hebei region at present.。

Yu'an No.3 Tunnel is the key project of Jinxing Railway.，The total length is 2513 meters，The shield section is 2080 meters.，The main crossing stratum is clay layer.，Segment OD 12.3 meters，Inside diameter 11.3 meters，The maximum buried depth is about 17 meters.，The minimum overburden thickness is less than 8m.，The tunnel underpasses the south embankment of Yongding River.。This project has a large excavation section.、The construction distance is long、Formation viscosity is strong、Gao Fu Shui、Difficulties such as shallow soil covering，Shield construction is difficult.。

Railway Construction Heavy Industry R & D technicians combined with the engineering geological and hydrological conditions of the project，Many technical difficulties have been overcome.。In order to better control the excavation face pressure,，Maintain surface stability，R & D technicians make targeted configuration of equipment，O as to cope with the problem that the long-distance clay stratum is easy to form a mud cake.、Initial settlement control for shallow burial、The formation is rich in water and prone to problems such as gushing.，The risk of shield construction is effectively reduced.。

  

“Xing'an”The shield machine is accepted and offline

“Xing'an”It only takes two months for the shield machine to leave the factory.，Through the close cooperation between the members of Jinxing Project of the 12th Bureau of China Railway and the service team of China Railway Construction Heavy Industry，Jointly completed the assembly and commissioning of the large-diameter earth pressure balance shield machine。

During the process，Service team targets customer nodes，All working faces are deployed simultaneously.。Under the powerful organization of Jinxing Project Department of China Railway 12th Bureau，The daily regular meeting shall discuss and formulate the daily node plan according to the site conditions.，Continuously optimize the installation process and technology，Step through the node target，Ensure the progress of construction period。Split commissioning scheme is adopted，Ensure that assembly and commissioning are carried out simultaneously，The assembly time of that equipment is greatly shorten。Full development of service team members“Not afraid of hardship，Not afraid of tiredness”The spirit of，Under the scorching sun，Resist the intense heat，Work overtime to assemble and debug the equipment，Finally guaranteed“Xing'an”Smooth start of shield machine。