China Railway Construction Heavy Industry Co., Ltd.: Connecting "Beijing-Tianjin-Hebei", the Largest Diameter Earth Pressure Balance Shield Machine "Xing'an" in Northern China Reaches a New High Tunneling Speed

Large-diameter earth pressure balance Shield Machine jointly built by China Railway Construction Heavy Industry and China Railway 12th Bureau“Xing'an”Since the smooth start，It is the first time to break through the good result of 520 meters per month.。

“Xing'an”Since September 8, 2022，A total of 1100 meters have been excavated.，Average daily footage 13.75 meters，The average daily footage in the effective driving time reached 16..18 meters，The tunneling speed reaches the highest of the same type of large-diameter EPB Shield Machine made in China.。

Earth pressure balance Shield Machine with that lar diameter in northern China“Xing'an”Originating

Jinxing Railway is connected to Tianjin.、Beijing Daxing International Airport and an important artery in the downtown area of Beijing，After completion, Tianjin and Xiongan New Area and Beijing Daxing International Airport will be accessible within half an hour.。“Xing'an”As the largest diameter earth pressure balance shield machine used in Beijing-Tianjin-Hebei region，The shield section is 2080 meters long.，The minimum overburden thickness is less than 8m.，The tunnel underpasses the south embankment of Yongding River.，Shallow burial depth near the starting well。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，And large diameter earth pressure shield is easy to cause large stratum disturbance.、Difficult control of soil chamber pressure and the like.，The construction is difficult。

“Xing'an”Box culvert laying site

In order to overcome the above difficulties,，Railway Construction Heavy Industry R & D technicians carry out targeted design of equipment，The first slag tapping system of parallel double spiral machine in China has been developed.，More accurate control of excavation chamber pressure，Maintain surface stability。Compared to single screw configuration，The parallel double screw machine has the advantages of 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 construction,，It also further improves the construction efficiency.。

“Xing'an”Acceptance offline

“Xing'an”It has been more than 80 days since its launch.，The accumulated excavation mileage has been more than half.，The overall operation of the shield is good.，Tunneling footage is gratifying。Successful Application of the Largest Diameter Earth Pressure Balance Shield Machine in Northern China，It provides more reference for similar large diameter EPB shield construction in the future.。

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