China has rolled out a super-large-diameter slurry shield machine that will be used to build Nanjing’s first high-speed railway tunnel beneath the Yangtze River, marking a key step in a major cross-river transport project.
The machine is designed to operate under deep water and high pressure as engineers work on a tunnel intended to improve rail connections through eastern China. The project also reflects the growing use of large tunnel-boring systems in China’s high-speed railway network.
Giant Machine Takes Shape
The shield machine recently left its production line in Hangzhou, Zhejiang province, according to the official WeChat account of China Railway Group. It measures 13.72 metres in diameter and 145 metres in length, making it one of the largest machines of its type developed for high-speed railway construction.
READ ALSO: https://modernmechanics24.com/post/japan-hypersonic-arms-race-china/
China Railway Engineering Equipment Group and China Railway Tunnel Group jointly developed the machine for the project. Its large cutting diameter is designed to create enough underground space for a single tunnel carrying two railway tracks, while its slurry-based system helps maintain stability as excavation takes place in difficult ground conditions.
The machine also features a double-layer shell, designed specifically for the challenges of the project. After tunnelling is completed, workers will remove the inner shield and backup equipment while leaving the outer shell in place as permanent structural support.
Tunnel Runs Deep
The Nanjing high-speed railway cross-river project stretches for about 20.4 kilometres, with around 14 kilometres made up of tunnel sections. The main passage is planned as a single-tube, double-track tunnel capable of carrying high-speed trains in both directions.
A major challenge is the length of the route running beneath the Yangtze River bed. At its deepest point, the tunnel will be buried about 107 metres underground and face water pressure of up to 1.07 megapascals, according to the project details.
That combination makes the tunnel the deepest and highest-pressure railway shield tunnel along the Yangtze River to date. For comparison, the machine will have to maintain a stable working environment while cutting through ground far below the river and managing the pressure created by the water above.
WATCH ALSO: https://modernmechanics24.com/post/lockheed-martin-grizzlymissile-launcher/
Two Machines Meet
Construction of the cross-river section will involve two slurry shield machines working from opposite ends of the tunnel. They are scheduled to advance toward each other before completing a high-precision connection beneath the north-bank floodplain.
The machines are expected to meet and be dismantled at a depth of about 30 metres below the floodplain area. The double-shell design is intended to make this process more manageable because the outer section can remain underground instead of requiring the entire machine to be recovered.
Such arrangements are particularly important in confined underground environments, where removing a complete shield machine can require additional excavation and complicated recovery work. Leaving the outer shell in place is intended to reduce the amount of equipment that needs to be extracted while allowing subsequent construction work to proceed.
Rail Links Gain Importance
The Nanjing project is designed to address a long-standing constraint on railway crossings over the Yangtze, one of China’s major transport corridors. By adding a high-speed rail crossing beneath the river, the project is expected to strengthen connections across Nanjing and support the movement of passengers between areas on both sides of the waterway.
The tunnel is also part of the wider transport infrastructure supporting the Yangtze River Economic Belt. The region is one of China’s main economic zones, and its regional gross domestic product has more than doubled over the past decade while authorities have placed greater emphasis on ecological protection and greener growth.
WATCH ALSO: https://modernmechanics24.com/post/tallest-dam-nears-full-power-capacity/
The use of a large slurry shield machine allows engineers to build beneath the river without constructing an open crossing through the waterway. However, the project will provide a test of China’s ability to manage deep, high-pressure underground railway works while expanding its high-speed rail network.
One Response