What are the technological innovations of the Hong Kong-Zhuhai-Macao Bridge?Oct. 30,2019
Hong Kong-Zhuhai-Macao Fixed Link Project is the longest sea-crossing fixed link project with a design service life of 120 years. This project will also symbolize the close ties between mainland China, Hong Kong, and Macao under the “one country, two system” policy. The main bridge and tunnel (except the approach to the bridge) of the Hong Kong-Zhuhai-Macao Fixed Link Project crosses the open sea of Lingdingyang Bay. The project was launched at the end of 2009 as announced by Li Keqiang, the former Vice Premier of the State Council. The project was nearly 55 km long, consisting of a 36 km sea-crossing bridge, two artificial islands (the east artificial island and the west artificial island, each 625 m long and about 100 000 m2), and a 6.7 km undersea immersed tube tunnel. Among them, the immersed tube tunnel, located 40 m below the sea level, is the longest and deepest immersed tube tunnel in the world. So far, the Hong Kong-Zhuhai-Macao Fixed Link Project has been completed and is ready for traffic.
Why an undersea immersed tube tunnel was selected for the sea area of the main channel of the east side of the project, instead of employing a sea-crossing bridge or undersea shield tunnel? What are the major technological innovations in the design and construction of the artificial islands and the tunnel? Which is the main technical issues to be highlighted for the immersed tube tunnel during long-term operation in the future?
Scientific and Technological Innovation and Operation-related Issues for Island-Tunnel of Hong Kong-Zhuhai-Macao Fixed Link Project by SUN Jun, Summed up his conclusions.
The result shows that 1. Early in the 1990s, a cross-sea bridge was proposed as only Hong Kong and Zhuhai were considered to be connected, later, as the Macao SAR joins in, the bridge site moved south outward, and subsequently the follow-up study of the bridge solution was terminated. Since the current bridge site is restricted by the clearance requirements for aircrafts taking off from the Lantau Airport of Hong Kong, and affected by a number of non-parallel crossing channels in the eastern sea area of the Lingdingyan Bay, the bridge solution in this sea area has to be abandoned finally due to the high technical difficulty to construct the bridge span structure. 2. A high cost for customizing the TBM from foreign manufacturers, and the delivery of the TBM may be too late. Therefore, there is no further study of the shield tunnel solution.3. The undersea immersed tube tunnel as the optimal solution for the sea area of the eastern navigation channel. the author believes that there are three reasons for selecting the immersed tube tunnel. Their structural strength and impermeability are guaranteed. The project is located deep in the ocean, the overall progress of the project will not be delayed even all marine operations are suspended during unexpected and unfavorable weather. This sea area belongs to offshore and shallow water areas, provide good conditions for maintaining element safety and stability when tube elements are sunk onto the seabed.
The author pointed out that Several domestic and global leading innovative technologies for island-tunnel construction of the Hong Kong-Zhuhai-Macao Fixed Link Project: 1. Huge self-stabilized steel cylinders used as retaining structure for deep and large foundation pits at sea to build artificial island; 2. Large-area and ultra-deep “SCP composite foundation” reinforcement technology; 3. Utilization of “semi-rigid joint of the tube segment”; 4. “Sandwich” steel-reinforcement concrete composite structure inverted-trapezoidal closure joint; 5. Crack control and anti-corrosion durability design of the reinforcement concrete immersed tube structure; 6. Construction technology combined with Chinese wisdom and China speed.
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