China completes massive TBM for Yangtze River high-speed rail tunnel

China has completed the production of a massive tunnel boring machine (TBM) named ‘Linghang’ for a high-speed railway project under the Yangtze River in Nanjing. Developed jointly by China Railway Engineering Equipment Group and China Railway Tunnel Group, the machine is designed to handle extreme underwater conditions.

The project involves a tunnel approximately 20.4 kilometers long, with a 14-kilometer section containing two high-speed railway lines within a single tube. The most challenging segment will pass beneath the Yangtze River at depths of up to 107 meters, where water pressure is expected to reach 1.07 megapascals. This will make it the deepest and highest-pressure railway shield tunnel constructed along the river to date.

Two 145-meter-long machines will be used to excavate from opposite sides of the river, meeting with high precision 30 meters below the northern floodplains. Due to the scale and difficulty of the environment, the machines feature a unique double-layered body design. Once excavation is complete, the internal shields and rear systems will be removed, while the outer shells will remain in place to serve as a permanent underground support structure.