On March 22, Guangdong Transportation Group announced that at 3 p.m. on March 21, after nearly 27 hours of continuous work, the 8th tube section (E8) of the immersed tube tunnel of the Shenzhen-Zhongshan Link, a core project in the Guangdong-Hong Kong-Macao Greater Bay Area, achieved precise underwater docking at a depth of 36 meters. With this, 1,278.5 meters of the immersed tube tunnel of the link's island-tunnel project has been completed, reaching one-quarter of the total immersed tube length (5,035 meters).

The E8 tube section installed this time is a standard tube section, 165 meters long, 46 meters wide and 10.6 meters high, weighing about 80,000 tonnes. Its immersion position is close to the deepest point of the entire line, and construction in the deep-water trench is complex and highly difficult.

At the same time, the E8 tube section is also the first immersed tube of the Shenzhen-Zhongshan Link to adopt daytime floating transport, nighttime mooring and daytime docking. “The main reason is that daytime docking coincides with the most active phase of the ionosphere, which can easily cause signal instability or even loss of lock, adversely affecting the control of installation accuracy during tube section docking. Measures such as introducing the BeiDou positioning system and strengthening monitoring were taken to ensure smooth docking.”

At around 3 p.m. on March 21, after nearly 27 hours of continuous work, the E8 tube section was successfully docked. Breakthrough measurements showed that the docking deviations of the E8 tube section were all within 50 millimeters, meeting the acceptance control standards.

The Shenzhen-Zhongshan Link is about 24 kilometers long in total and is scheduled to be completed and opened to traffic in 2024. Its undersea tunnel is about 6.8 kilometers long, including an immersed tube section of about 5 kilometers. It adopts a steel-shell concrete composite structure, the first of its kind in China and the first large-scale application internationally, and consists of 32 tube sections and one final joint. It is currently the world's widest undersea immersed tube tunnel.

Song Shenyou, deputy director and chief engineer of the Shenzhen-Zhongshan Link Management Center, said that preparations will next be made for the immersion and installation of the E9 tube section, which will be installed at a depth of about 40 meters, the deepest installation waters along the entire line. According to plan, the first tube section on the east side of the project's immersed tube tunnel will be immersed in August this year. This will be the first immersion construction of an ultra-wide variable-width tube section along the entire line and is technically highly challenging.