The recently completed mega sea crossing, the Shenzhong Link Project, has set ten new world records in bridge and tunnel construction. Trelleborg’s groundbreaking M-seal is among the record holders.
After seven years of construction, a massive infrastructure project linking the two sides of the Pearl River Delta in southern China opened to traffic on June 30, 2024. The 24-kilometer ShenZhong Link consists of two artificial islands, two high-level bridges, a causeway, and the world’s widest undersea immersed tunnel. It connects the cities of Shenzhen to the east of the delta and Zhongshan to the west. The tunnel section has four traffic lanes in each direction with a capacity of 90,000 cars per day.
“The design of such a large-scale tunnel not only required more complex construction techniques, but also places extremely high demands on structural safety and operation,” says Eddy Chen, Sales Director for Trelleborg’s infrastructure business in China.
The tunnel in the ShenZhong Link consists of 32 huge construction elements, each weighing up to nearly 80,000 tons, as long as two soccer fields and as high as a three-story building. Fabricated on land and then floated and towed to the tunnel alignment, the elements are sunk into place and then linked together as a tube. Trelleborg’s gaskets, seals, and waterstops are critical parts of this linking process to make the tunnel completely waterproof.
“Such large, immersed elements require extremely precise docking and installation, which greatly increases the complexity of construction,” says Louis Yuan, Design Manager at Trelleborg’s infrastructure operation in China.
The Trelleborg facility in Qingdao produced all of the gaskets, seals, and waterstops for the ShenZhong Link, including the groundbreaking M-seal and inflatable seal used for the tunnel’s closure joint.
“The M-seal solution that we designed and produced for the closure joint was one of the keys to ensure that the project went smoothly, and the immersed element was fully sealed,” says Yuan.
“The M-seal is not only the largest expandable waterstop of its kind in the world, but also the first one produced by Trelleborg in China,” says Chen.
A big part of the construction took place when China had heavy travel restrictions because of the pandemic,” Chen says. “During this period, most of our colleagues in the Netherlands who normally lead on such projects could not travel, so our Qingdao team took a lot of responsibility and we managed to always deliver on time.”
Such a high-profile project always presents challenges. One was that the waters of the Pearl River Estuary, the location of the ShenZhong Link, have complex currents and large tidal changes. The deepest immersed element installation reached a depth of more than 40 meters. This and the complex geology of the delta’s bed increased the difficulties of docking, installation, and sinking of the immersed elements.
The region is also threatened by natural hazards such as typhoons and earthquakes. “Therefore, the design of the ShenZhong Link focused on strengthening its resistance to seismic movement and wind, ensuring its stability in extreme weather and geological conditions,” says Yuan.
After completing this mega project, the Trelleborg team is now actively working on several new tunnel projects in Guangdong Province. “We are proud and gratified to witness the rapid development of China’s infrastructure and to see that people’s lives have become easier as a result,” says Chen.
Learn more about solutions for immersed tunnels at Trelleborg.com.
