China's biggest Tunnel Boring Machine is tunneling under Yangtze River in impressive penetration rate. Diameter is 16.64 meters. Developed jointly by China Railway Construction Heavy Industry Co (CRCHI) and China Railway 14th Bureau Group Co.

145 Meter long Jianghai is largest domestically developed and produced TBM in China.  145 meters and 5000 tons.

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, 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 1 centimeter. The construction difficulty is great, and the geological exploration coverage in the river is limited, with many uncontrollable 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 and problem 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 innovative 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, assisting the cutter head to break out, and 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 basically 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.

Please read English news.

https://www.bastillepost.com/global/article/4390120-innovative-tunneling-machine-propels-chinas-modern-construction

I use text from CRCHI press release https://en.crchi.com/art/2024/11/1/art_40592_5009184.html