Recently，Composite Earth Pressure Balance Shield Machine Jointly Built by China Railway Construction Heavy Industry and China Railway 14th Bureau Single-head Tunneling 13.8 kilometers，Successfully through the construction section of a water conveyance project in China，Set a new record of single-head shield tunneling in China。

Equipment-assisted tunnel penetration

It is reported that，The water conveyance project is the first water conservancy project constructed by earth pressure shield method in China.，The composite earth pressure balance shield machine is the first shield machine of the project.，It is also the first shield machine in the whole tunnel.。The buried depth of the tunnel in the construction section of the equipment is between 60~Between 112 meters，The requirements for the sealing performance and compression resistance of the shield machine are high；The total length of single-head tunneling of shield machine is 13.8 kilometers，The tunnel passes through complex strata.，The construction is difficult，The requirements for the performance of the shield machine are extremely high.；Groundwater pressure reaches 7 bar，That's seven kilograms of pressure per square centimeter of surface.，Tunneling construction with high water pressure is another difficult problem in this project.；Continuously crossing strong swelling surrounding rock stratum，The free swelling rate of mudstone is 83%～98%，It is the first time in the field of shield construction.。

To solve the problem of high water pressure、Large burial depth、Difficult construction problems such as long-distance tunneling，The R & D and design personnel of Railway Construction Heavy Industry have made a large number of targeted designs for the composite earth pressure balance shield machine.，Capable of effectively bearing high water pressure、Resisting the convergence of the surrounding rock、Coping with continuous ultra-long distance tunneling。The average monthly footage of the equipment during construction is 601 meters.，Maximum monthly footage 842.4 meters，Construction efficiency has been improved in an all-round way.。

Composite earth pressure balance shield machine

The total line length of the project is 43.786 kilometers，Of which 21.Three composite earth pressure balance shield machines are used for the construction of 769 km.，The composite earth pressure balance shield machine is the first shield machine.，It successfully completed the longest single heading 13.An eight-kilometer mission.。The second and third shield machines also performed well.，Successively in 2020、In 2021, the construction interval tunnel was completed.。

In the face of strong wind and sand、High altitude、Challenges brought by the harsh construction environment such as ultra-low temperature and severe epidemic prevention and control，The experienced service team of China Railway Construction Heavy Industry Co., Ltd. and the professional construction team of China Railway 14th Bureau Co., Ltd.，Carry forward“Especially able to bear hardships、Especially patient、Especially able to fight”The spirit of the Iron Army，All kinds of difficulties in the project construction have been overcome.，Under extremely complicated geological conditions，The goal of smooth construction of high-quality projects，It fills in the blank of ultra-long distance rapid construction of shield machine under high and complex geological conditions in China.。