China Breaks World Record: Digs the Deepest Undersea Tunnel in History for High-Speed Trains
The high-speed railway tunnel beneath the southern Chinese seabed has set a new world record for tunnel depth. China has excavated the deepest undersea tunnel ever built for high-speed rail, with the Shenjiang No.1 tunnel boring machine operating continuously for four years, advancing over 4 kilometers. This monumental project will connect the cities of Shenzhen and Jiangmen, reducing travel time between them to less than one hour.
Beneath the southern Chinese sea, a tunnel boring machine is advancing at a depth exceeding 100 meters. The project has just broken the world record for depth in undersea railway tunnels.
China is carving out the deepest undersea tunnel in history, linking two southern Chinese cities—Shenzhen and Jiangmen.
China is currently excavating the deepest undersea tunnel ever for a high-speed railway. At 116 kilometers long, the journey between the two cities will take less than one hour once completed.
The Pearl River Estuary Tunnel is the centerpiece of the entire construction site. According to CGTN, the drilling machine reached a depth of 113 meters below the seabed in April 2026—a new world record for high-speed rail tunnels. The planned maximum depth of 116 meters presents enormous challenges due to extreme hydrostatic pressure constraints.
The Shenjiang No.1 tunnel boring machine was designed and manufactured in China, having operated continuously for four years and advanced over 4 kilometers. It must pass through 13 distinct geological layers, five complex geological formations, and six fault zones. As such, this underwater tunnel faces unprecedented complexity among such construction sites.
The Shenjiang No.1 tunnel boring machine has pushed the limits of underwater civil engineering. At such great depths, hydraulic pressure exerts immense stress on machinery and structures. To overcome this challenge, the Shenjiang No.1 employs a dual slurry circuit system. The first circuit delivers slurry to the cutting head to reduce friction. The second circuit transports excavated soil to the surface for processing and then reuses it in tunneling operations.
Behind the drilling machine, construction teams are continuously assembling precast concrete segments—these form the lining and waterproof covering of the underwater tunnel. Each segment is about two meters wide. With a tunnel diameter exceeding 13 meters, nine segments are required to complete a full circular ring structure.
Excavation and Construction Proceed Simultaneously
This synchronized approach enables real-time excavation and construction. Consequently, despite the complex terrain, progress remains steady. The tunnel spans 13.69 kilometers, connecting Dongguan and Guangzhou, crossing multiple waterways at the confluence of the Pearl River.
This record-breaking undersea tunnel will further strengthen economic integration across southern China. The project is a crucial component of the Greater Bay Area’s integration strategy. The Greater Bay Area is one of the most dynamic economic regions globally. Thus, this undersea tunnel represents not only an engineering challenge but also a vital lever for promoting regional integration.
Upon completion, the Shenzhen-Jiangmen high-speed railway will link with China’s coastal railway corridor. China possesses the world’s largest high-speed rail network, with track length exceeding 45,000 kilometers. This achievement demonstrates China’s capability to push the boundaries of engineering technology even in extreme environments.
Source: rfi
Original article: toutiao.com/article/1863224771168266/
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