Record Rewritten! Chinese-made Largest Diameter (16.64 -m) Shield Machine ‘Jianghai’ Rolls off at CRCHI

On October 31, 2024, a super-large diameter shield machine with a maximum excavation diameter of 16.64 meters rolled off the production line in Changsha, Hunan. It will be used in the construction of the world's longest underwater highway shield machine tunnel – the Haitai Yangtze River Tunnel. This follows the domestic first 16-meter class super-large diameter shield machine "Jinghua," as CRCHI surpasses itself and sets a new record, creating Chinese-made largest diameter shield machine developed independently to date, marking a new breakthrough in the development of super-large diameter shield machines.
This shield machine, named Jianghai, is about 145 meters long and weighs approximately 5,000 tons. Jianghai is named by integrating the two concepts of crossing the Yangtze River and being adjacent to the sea in the Haitai Yangtze River Tunnel project. Its cutter head is painted with blue waves moving forward, symbolizing that the shield machine will gather strength to dive and traverse the rivers and seas.
The Haitai Yangtze River Tunnel is located in the Yangtze River estuary area of Jiangsu Province, starting from Haimen District in Nantong in the north and ending in Taicang City in Suzhou in the south. The total length of the project line is 39.07 kilometers, with the cross-river tunnel being 11.185 kilometers long. It is designed with a two-way six-lane highway standard, with a design speed of 100 kilometers per hour. The tunnel section is 9,315 meters long, with a maximum excavation diameter of 16.64 meters. Along the route, it needs to pass through complex geological belts such as silty clay, silty clay interbedded with silt and fine sand, with a maximum burial depth of about 75 meters, and the highest water pressure reaching 7.5 bars. It features ultra-long distance, an ultra-large diameter, ultra-high-water pressure, ultra-deep burial, and complex working conditions.
Jianghai will complete the ultra-long-distance single-headed tunneling underwater in the Yangtze River, especially when crossing the Yangtze River and the dikes on both sides, the settlement requirement is controlled within one centimeter. The construction is very difficult, and the geological exploration coverage in the river is limited, with many uncontrollable and unknown areas.
The ultra-16.64-meter large diameter means that the shield machine cutter head requires a large torque for excavation, and the main drive bearing load is large. The 7.5 bar ultra-high water pressure requires high pressure-bearing capacity for components such as the main drive seal and the tail seal.
How to ensure the continuous tunneling of the entire machine for 9,315 meters in the complex environment at the bottom of the river while maintaining high-performance load is the main challenge faced by the R&D team. In response to the construction risks and difficulties of the project, the R&D team has made purposed designs on key parts such as the cutter head and the main drive through research. It is equipped with a soft soil cutter head with accessible cutter head and alloy cutters that are large, hard, widely covered, and wear-resistant. The main drive is equipped with a telescopic function that can sense the overall force of the cutter head, effectively avoiding abnormal force on the cutter head caused by overload of the main bearing under special circumstances, facilitating cutter change operations, and assisting the cutter head to break out. It is equipped with a main drive status monitoring system to continuously monitor the operating status of the main drive.
At the same time, the shield body size and structural thickness are designed according to local conditions, the oil cylinder specifications are increased, the slurry circulation system and grouting system are optimized, etc., to enhance the overall performance of the machine, and a smart assembly system for segment connection components is configured to meet the construction requirements.
The Haitai Yangtze River Tunnel is a key construction project and is planned to be completed in 2028. After completion, it can effectively divert the traffic of the Suzhou-Nantong Yangtze River Bridge, which is of great significance for optimizing the layout of the Yangtze River mainstream crossing channels.