China unveils 5,000 metric ton-heavy tunnel boring machine with largest-diameter

Nov 02, 2024

The new TBM will construct a tunnel beneath the Yangtze River in Jiangsu province, connecting Nantong and Suzhou.

Jijo Malayil

A TBM developed by CRCHI for operations in Romania.

CRCHI

China has completed the production of its largest tunnel-boring machine (TBM), measuring 16.64 meters (54.5 feet) in diameter.

The machine is named Jianghai, which means “river and ocean” in Chinese. It weighs approximately 5,000 metric tons (11 million pounds) and is 475 feet (145 meters) long; it is the largest tunnel-boring machine designed in China.

The machine was built in Changsha, Hunan Province, through a collaboration between China Railway Construction Heavy Industry (CRCHI) and China Railway 14th Bureau Group.

In May, China claimed to have developed the world’s first boring and blasting machine (BBM) that offers 30 percent more efficient tunneling.

The new TBM will be used to build a tunnel across the Yangtze River in Jiangsu province, linking Nantong and Suzhou.

The tunnel is part of a 24-mile (39-kilometer) highway expected to be completed by 2028. Spanning approximately 7 miles (11.2 kilometers) beneath the Yangtze River, it will reach depths of up to 246 feet (75 meters).

According to You Shaoqiang, the project chief engineer at China Railway 14th Bureau Group (CR14G), the tunnel faces challenges due to underground water sources, soft soil, and silt, making traditional manual tunneling impossible, reports news publication China.org.

The advanced TBM will progress at a rate of 12 to 16 meters (39 to 52 feet) per day, and tunneling is projected to take about two and a half years. As the tunnel lies near the Yangtze River estuary, tunneling precision must stay within 1 centimeter (0.4 inches) to ensure the safety of river dams.

The machine is 476 feet long and weighs about 5,000 tonnes (11 million pounds), with a cutter head diameter comparable to a five—or six-story building. CRCHI chairman Zhao Hui stated that this development represents a significant achievement in the industrialization of 16-meter-class, large-diameter tunnel boring technology in China.

In 2022, a 16.07-meter (52.7 feet) diameter TBM was produced by CRCHI and China Railway 14th Bureau Group (CR14G) for a renovation project in Beijing.

According to CRCC senior engineer Fan Ruiqiang, the team spent over two years developing the new, larger TBM. This advanced machine is more intelligent, featuring a database that logs past tunneling issues, allowing it to offer drivers suggestions when similar challenges arise, according to China.org.

Wang Jun, deputy head of the Jiangsu transport project construction bureau, noted that this TBM represents a critical step for Jiangsu’s highway project, a major transport initiative for the province. Wang added that this machine is a significant breakthrough for China’s manufacturing industry, reflecting both engineers’ hard work and the nation’s progress in large-scale machinery production.

The BBM system, unveiled in May, was developed by China Railway Science & Industry Group Corporation and Tsinghua University’s National Key Laboratory of Hydroscience and Engineering. The system uses completely different drilling and blasting methods and is claimed to be a boon for water conservation, mining, railways, and highway projects.

The new TBM is designed to perform in challenging fault fracture zones and withstand sudden mud or water inflows. Its ring cutter head enables excavation in extreme conditions, while a dual-mode operation allows simultaneous drill and blast methods, improving speed and efficiency.

The hollow cutter head facilitates navigation through complex geology. Tsinghua University researchers see extensive applications in water conservancy, hydropower projects, mining, and infrastructure, positioning China as a leader in advanced tunneling technology.According to a trial’s findings, “the hollow cutter head’s efficiency can be increased by 30 percent after pre-cracking treatment under extremely hard rock conditions.”

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Jijo Malayil Jijo is an automotive and business journalist based in India. Armed with a BA in History (Honors) from St. Stephen's College, Delhi University, and a PG diploma in Journalism from the Indian Institute of Mass Communication, Delhi, he has worked for news agencies, national newspapers, and automotive magazines. In his spare time, he likes to go off-roading, engage in political discourse, travel, and teach languages.

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