Recently, the composite earth pressure balance shield machine jointly built by CRCC and China Railway 14th Bureau has excavated 13.8 kilometers by itself, successfully passing through the construction section of a domestic water conveyance project, setting a new record for single-end excavation of shield tunneling in China.

Equipment assists tunnel penetration

It is reported that the water transfer project is the first domestic water conservancy project constructed by the earth pressure shield method. The composite earth pressure balance shield machine is the first shield machine of the project and the first shield machine of the entire tunnel. The buried depth of the tunnel in the construction area of this equipment is between 60 and 112 meters, which requires high sealing performance and compressive capacity of the shield machine; the total length of the single-head tunneling of the shield machine is 13.8 kilometers, and the tunnel crossing the stratum is complicated and difficult to construct , the performance requirements of the shield machine are extremely high; the groundwater pressure reaches 7 bar, which is equivalent to a pressure of 7 kg per square centimeter of the surface. High water pressure excavation construction is another difficult problem in the construction of this project; In the surrounding rock formation, the free expansion rate of mudstone is 83% to 98%, which is the first time in the field of shield tunneling.

In order to solve construction problems such as high water pressure, large buried depth, and long-distance excavation, the R & D and design personnel of China Railway Construction Heavy Industry carried out a large number of targeted designs for the compound earth pressure balance shield machine, which can effectively withstand high water pressure and resist surrounding rock. Convergence and response to continuous ultra-long-distance excavation. During the construction period of the equipment, the average monthly footage was 601 meters, and the maximum monthly footage was 842.4 meters. The construction efficiency has been comprehensively improved.

The total length of the project line is 43.786 kilometers, of which 21.769 kilometers are constructed by three composite earth pressure balance shield machines. km task. The second and third shield machines also performed well, and completed the tunnel breakthrough in the construction section in 2020 and 2021.

Faced with the challenges brought about by the difficult construction environment such as strong wind and sand, high altitude, and ultra-low temperature, as well as the severe epidemic prevention and control, the experienced CRCC service team, together with the professional construction team of the China Railway 14th Bureau, carried forward the "special ability to endure hardship, special ability The Tiejun spirit of “Patience, Especially Fighting” has overcome all kinds of difficulties in the project construction. Under the extremely complex geological conditions, the goal of successfully building a high-quality project has filled the gap between the super-long shield machine in my country under highly complex geological conditions. Blank from quick construction. Editor/He Yuting