According to an official Weibo post by State-owned Assets Supervision and Administration Commission, the Qingdao Jiaozhou Bay Second Tunnel, the largest undersea highway tunnel constructed in the world, has officially started shield tunneling operations.According to reports, the shield excavation distance is 3,255 meters, and it is excavation from the Qingdao Port Terminal to the west coast. It will be connected with the drilling and blasting section tunnel, and the shield machine will be received and dismantled in the seabed cavern.
The geological conditions on the seabed of Jiaozhou Bay are complex. The shield machine enters the sea immediately after setting off, and needs to traverse complex and changeable, unevenly soft and hard strata and fault zone strata over long distances. The "Haitian" shield machine used in the project has a total length of 142 meters, a total weight of 4,275 tons, and an excavation diameter of 15.63 meters. It is equipped with a series of intelligent systems such as a telescopic main drive and a telescopic excavation bin monitoring system.
It is understood that the Jiaozhou Bay Second Tunnel Project starts from the West Coast New District of Qingdao in the west, crosses Jiaozhou Bay in the east, and lands near Qingdao Port. It connects the urban area on the east coast of Qingdao in the form of an elevated bridge. The main line is 17.48 kilometers long.
The tunnel is 14.37 kilometers long, including a sea section of 9.95 kilometers. The main line tunnel shield machine excavation diameter is 15.63 meters, and the deepest point is 115 meters above sea level.The tunnel construction adopts the layout of two main tunnels and an intermediate service tunnel. It is constructed as a two-way six-lane urban expressway with a design speed of 80 kilometers per hour.
In addition, the Jiaozhou Bay Second Tunnel is a main line tunnel plus an intermediate service tunnel. It has the function of a cross-sea passage for passenger and freight vehicles. The total amount of earth and stone excavated exceeds 6 million cubic meters, surpassing the Seikan Undersea Tunnel in Japan and the Channel Tunnel. It is also the largest cross-section undersea tunnel that combines the drill and blast method and the shield method.