China has completed production on its largest-ever tunnel-boring machine (TBM), named Jianghai, meaning “river and ocean” in Chinese. This giant machine measures 16.64 meters (54.5 feet) in diameter and spans 475 feet (145 meters) in length, weighing approximately 5,000 metric tons (11 million pounds). Built through a partnership between China Railway Construction Heavy Industry (CRCHI) and China Railway 14th Bureau Group, Jianghai is the most massive TBM developed domestically in China to date.

The new TBM is set to tackle a challenging tunneling project beneath the Yangtze River in Jiangsu Province. The machine will bore a tunnel linking Nantong and Suzhou, a key section of a planned 24-mile (39-kilometer) highway scheduled for completion by 2028. At a depth of up to 246 feet (75 meters), the tunnel will extend roughly 7 miles (11.2 kilometers) under the Yangtze River. Due to the difficult terrain, which includes soft soil, underground water, and silt, traditional manual tunneling is unfeasible. Instead, Jianghai will proceed at a daily pace of 12 to 16 meters (39 to 52 feet), with the entire tunneling phase expected to last two and a half years. Precision is crucial for the project; to protect nearby river dams, the TBM’s path must stay within 1 centimeter (0.4 inches) of specifications.

The sheer size and sophistication of Jianghai are notable, with its cutter head diameter comparable to the height of a five- or six-story building. According to CRCHI chairman Zhao Hui, the TBM represents a major leap forward for China’s large-diameter tunnel-boring technology, which has been rapidly advancing in recent years. In 2022, a 16.07-meter (52.7 feet) diameter TBM from CRCHI was also utilized for a major renovation project in Beijing. The development team behind Jianghai, led by CRCC senior engineer Fan Ruiqiang, worked for over two years to create the highly intelligent machine, which includes a database that tracks past tunneling issues and provides real-time suggestions to operators.

Beyond its application in Jiangsu’s transport infrastructure, China’s ongoing innovation in tunnel-boring technology is underscored by the development of a new boring and blasting machine (BBM) launched in May. Developed in collaboration with Tsinghua University, the BBM offers a 30% boost in efficiency for projects in water conservation, mining, and transportation.

The Jianghai TBM, equipped with a ring cutter head and dual-mode operation, is specifically designed to function in complex geological conditions, such as fault fracture zones with mud or water inflows. Additionally, its hollow cutter head, developed at Tsinghua University, has been shown to increase operational efficiency by 30% after pre-cracking treatments in extremely hard rock.

The advancements of Jianghai and the BBM system demonstrate China’s expanding capabilities in large-scale engineering and position the country as a leader in advanced tunneling technologies.

By Impact Lab