Shenzhen-Zhongshan Channel, located at the core area of Pearl River Delta, is a world-class combination of “bridge, islands, tunnel and underwater interchanges”. It starts at the interchange of Guangzhou-Shenzhen Highway and Shenzhen Bao’an Airport, flies over the Pearl River Estuary, and lands at Ma’an Island of Zhongshan. The channel will be about 24km long, with 44.69bn yuan investment, and is expected to open in 2024.

After 15 years’ research and preparation, the construction starts this year. Recently, the designer and technical director of the project was interviewed and unveiled the technical secrets behind the construction.

Quick completion of the West Artificial Island

On September 18, as the last steel cylinder was precisely arranged under the sea with vibration sinking technique, the West Artificial Island of Shenzhen-Zhongshan Channel shaped up in only 4 months’ time.

“We planned to use 57 steel cylinders, 28m-wide each, to enclosure and fix the West Artificial Island on the sea bed. Then we will fill the area in-between with sands to make up the island body.” With this special technique, said project director of the West Artificial Island, a stable structure could be developed quickly in regardless of complex seabed structure and with less contamination.

The DSM (deep sea mixer) ship berthed at the construction site was the hero resolving geological problems of the construction of West Island, added Xu Bo.

“And have you seen the yellow arm over there? That is the 12-hammer combined vibration hammer group we developed.” Said Xu Bo. It was the hammer group who pushed all 57 steel cylinders, 600 tons each, into the bottom of the sea.

The first extra-long tunnel in the world

Vice-director of Shenzhen-Zhongshan Channel Administration Center and Chief Engineer Song Shenyou believed the construction of the 6.8km two-way eight-lanes extra-long subsea tunnel would be the most technically challenging part of the whole project.

Difficulties came up at the design stage of the interchanges within the tunnel. In order to resolve the visibility range problem, Song Shenyou and his team decided to use VR-like driving simulator, by which engineers could simulatedly “drive in the virtual tunnel” and collect related data.

After repeated comparisons and selections, the design team determined the steel-shelled concrete immersed tunnel structure, which is of strong carrying capacity, crack resistance and durability and less impact on ocean environment.

“Hopefully we will developed a new-type immersed tunnel structure, which can fill up the domestic technique blanks in this area.” Said Song Shenyou.　

Offshore extra-high suspension bridge

Lingding Channel Bridge, which spans 1666m, would be the first offshore extra-high suspension bridge in China. However, its design is restricted by air defense high limit and shipping restrictions, as the Bao’an Airport limits the height of the bridge towers and construction equipment and the navigation high levels of Lingding Ocean Channel and Fanshi Waterway determine the clear height of Lingding Channel Bridge.

“The main surface of the bridge would be 90m above the sea, making Lingding Channel Bridge the highest offshore bridge in the world.”