Huge concrete tube installed underwater in Liaoning

With the underwater placement of the first immense concrete tube in Dalian Bay, the ambitious tunnel being built in Liaoning province marked a milestone on Dec 9.

It took about 17 hours to place the tube, which was 135 meters long, 33.4 meters wide, 9.7 meters high, and weighed 410,000 tons.

The Dalian Bay Undersea Tunnel will have 18 immersed concrete tubes with a combined length of 5.1 kilometers. It is being built by First Harbor Engineering Co under China Communications Construction Co.

Zhang Haiying, an engineer on the project, said the tunnel is the northernmost of its kind in China, and cold weather demands higher standards for the frost resistance of concrete.

Compared with the construction of the Hong Kong-Zhuhai-Macao Bridge, the underwater topography and traffic diversion needs for the Dalian Bay project require higher requirements for the prefabrication and installation of submerged concrete tubes, he said.

To ensure the butt-joint installation of the tubes, the research and development team spent three years working out solutions to key technical difficulties, so as to ensure precise docking between the first immersed tube and the installed section on the north bank.

The Dalian Bay Undersea Tunnel is expected to be completed and put into operation in 2023 as a new north-south expressway for Dalian.