Schematic diagram of a cross passage TBM
Capable of launch, excavation, muck discharge, support, erection and receiving, CREG cross passage TBMs, including shield machine type and pipe jacking machine type, can excavate cross passages with different lengths and curve radiuses in main tunnels with different diameters. They are mainly used for soft ground, such as clay, mud, silty clay and silt.
CREG cross passage TBMs are featured with four technological innovations.
- Modular-designed machine integration technology. Integrated with excavation, muck discharge, support, erection, thrust, seal and material transferring functions, the cross passage TBMs can realize rapid mechanized excavation in a narrow space.
- Automatically controlled mobile segment support technology. Available to different tunnels, the support system can realize continuous pressurization and depressurization according to the tunnel fluctuating load so as to monitor, master and control the tunnel deformation in real time. To be specific, a) Jumbo with travelling mechanism: it is used to place the main machine and auxiliary construction devices, which can make the cross passage TBMs move rapidly under traction by locomotive; b) Support ring for tunnel protection: support system is controlled by hydraulic servo and can be used for real-time monitoring of tunnel deformation and variation of support pressure to ensure safety and stability of main tunnel.
- Tapered cutter head technology. Different from conventional a cutterhead, the cutterhead of a cross passage TBM is of tapered design, and its taper is similar to ID of segments of main tunnel. Center cutters first contact and cut the tunnel face during launching, and cutting tracks continuously expand all around as main machine tunnels forward. However, the radian of segments at the receiving side is opposite to the taper of cutterhead and in order to avoid deflection of the main machine, the center cutters are of reverse tapered design and the taper is similar to OD of segments at receiving side to ensure stable receiving of the main machine.
- Launch and receiving portal sealing technology for T-connected tunnel. The launch and receiving portals are sealed by the use of half sleeve and full sleeve, respectively to connect with the curved surface so that the entire construction process is in a closed environment, effectively avoiding water gushing into the tunnel.
Compared with the conventional mining method, the cross passage TBMs have been improved in construction safety and quality, and its efficiency is more than four times of the conventional mining method. At present, they have been successfully applied in more than 10 projects, including Ningbo Rail Transit Line 3, Wuxi Metro Line 3, and Australia West Gate Tunnel, and have excavated more than 100 cross passages.
- Ningbo Rail Transit Line 3
On Dec. 29, 2017, it was the first time to use a cross passage TBM (shield machine type) to excavate the metro cross passage in China. It took 18 days to break through the 17m long cross passage. After completion, the cross passage had a good quality with no water leakage phenomenon.
- Wuxi Metro Line 3
On Dec. 10, 2018, it was the first time to use a cross passage TBM (pipe jacking machine type) to excavate the metro cross passage in China. It took 16 days to break through the 14m long cross passage.
- Qingdao Metro Line 8
On Oct. 19, 2019, with 10.8m clear spacing, the cross passage TBM was launched and it took 17 days to break through. This project is the first submarine cross passage constructed by mechanized method in China.
- Hangzhou Airport High-Speed Railway
On Feb. 11, 2022, the cross passage TBM was launched and it took 12 days to break through. This project is the first cross passages excavated by the first dual mode cross passage TBM (pipe jacking machine type) in China, which overcame the construction difficulties of tunneling in large overburden and high water pressure stratum.