Since ancient times, Shanghai had been separated by Yangtze River into two islands, Congming and Changxing. The economy of the islands was seriously affected by the poor river-crossing transportation,. People had dreamed for a long time to build connections between the two islands across Yangtze River. After the development drive of Pudong, the third big island of China, Congming Island has also been listed as a key development region by China’s government. In 2004, Shanghai Yangtze River Tunnel and Bridge Project eventually commenced on Congming Island, which is a tunnel-bridge integrated project for linking Shanghai to Congming, as planned and studied for 10 years.
Shanghai Yangtze River Tunnel-bridge is the biggest river-crossing in China and the biggest tunnel-bridge integration project in the world. It includes Shanghai Yangtze River Tunnel (Nangang Tunnel), Shanghai Yangtze River Bridge (Beigang Bridge) and relevant connection roads. It is an important part of Shanghai-Xi’an Highway in the national key highway construction planning as defined by the Ministry of Transportation. It begins in the south from Shanghai Pudong District Wuhaogou (East Line) and Baoshan District Luojing (West Line), and ends at Chenjia Town of Congming Island, via Changxing Island, with a total length of 25.5km. The Shanghai Yangtze River Bridge links Congming Island and Changxing Island, with a length of about 10.3km. The Yangtze River Tunnel is connected to Changxing Island and the outskirt ring road of Shanghai, with a length of about 8.9km. The connection road for Changxing Island and Congming Island is about 6.3km long. During the period of executing Yangtze River Tunnel-bridge Project, Cong-Qi Expressway for linking Congming and Qidong is also under urgent study and expected to be completed and opened to traffic together with Yangtze River Tunnel-bridge and linked to Ning-Tong-Qi Expressway of Jiangsu Province. At that time, the two regions facing each other across the river, Congming of Shanghai and Qidong of Jiangsu will be connected thoroughly.
In the construction of the Shanghai Yangtze River Tunnel, advanced shield-tunneling equipment and modern tunneling means are used for mechanical automatic installation of tunnel segments at a tunneling speed of 15m per day. The tunnel has an inner diameter of 13.7m, outer diameter of 15m, deepest place of 55m, and primary tunneling length of 75km.
As another important part of Shanghai Tunnel-Bridge Project, the Shanghai Yangtze River Bridge is located in an extremely special geographic region. Since its site is selected at the utmost eastern part of the section suitable for bridge building on the two islands, Changxing and Congming, it is the first bridge built at the estuary of Yangtze River close to the East Sea as well as the last one of various river-crossings built downstream of Yangtze River. Hence, it is honored as “the No.1 Bridge at Gateway of Yangtze River”.
The Shanghai Yangtze River Bridge under construction is a cable stayed bridge with dual towers, dual cable planes and separate steel boxes, designed as per two-way navigation requirements for 30,000dwt containers carriers and 50,000dwt bulk carriers. Its cross-river section is up to 10km long and main navigation arch has a span of 730m. This standard exceeds any bridges already built in Shanghai and even over 300m bigger than the main navigation arch of Donghai Bridge. It ranks only the second to Sutong Bridge and Hong Kong Stonecutters Bridge in China and ranks the fifth in the world.
According to the introduction by Li Zongping, Executive Deputy Manager and Chief Engineer of Shanghai Yangtze River Bridge Main Bridge Project Management Office, the Shanghai Yangtze River Bridge has three prominent technical features. Maximum-span equal-section steel-concrete overlapped beams: with a length of up to 105m, the concrete overlapped beams for deck are the biggest equal-section steel-concrete overlapped beams in the world; the first highway-rail combined bridge: it is the first bridge with expressway and rail transit on one deck in the world. The middle part of the bridge is designed with highway, which can be used for buses; both sides of the highway are reserved for rail transit. In the future, Congming Island can be arrived from the new city area of Shanghai by rail transit. The main tower structure with most technical challenge: being different from the reverse Y-shape of Yangpu Bridge, A-shape of Xupu Bridge, and H-shape of Nanpu Bridge, the bridge adopts the herringbone beam-free arc tower column structure, as is the first application in China. Running through the waist line, the flat and straight bridge deck is of the great ornament.
In terms of construction method, they adopted the positioning guidance frame, an innovative pile-foundation guiding device made for Sutong Yangtze River Bridge, upon improvement according to the actual conditions of Shanghai Bridge, as has effectively controlled the positioning and verticality of guard sleeves and successfully resolved the accuracy problem of pile foundation in the deep-water area at the estuary of Yangtze River.
As for the design feature of the main tower with the herringbone beam-free arc structure, a new hydraulic climbing formwork machine was designed to adapt the arc requirement of the tower shape. This equipment could climb up in a straight line as well as on an arc track, making a new process in bridge construction.
For the purpose of improved construction accuracy , they designed the automatic aggregation and distribution equipment, with the automatic valve installed below the hopper of the pouring concrete, which can adjust the opening size, to regulate the usage of concrete. Since this design was more scientific and rational than the previous concrete pouring procedure, the concrete pouring process could be more easily operated as well as contamination was reduced; the scalable “corbel” was welded inside the guard sleeve to ensure the accurate lowering of the steel suspension box and effectively prevent any displacement of the steel suspension box being lowered; in the integral hoisting and whole-piece settling works for the steel guard sleeves, the binding-type hoisting method was used, with two main hooks, of which one was meant for lifting and the other for lowering, vertically instead of horizontally, to effectively prevent the steel guard sleeves from deformation due to force; in order to resolve the problem of inconvenient service of concrete for the main towers, a kind of automatic spraying device was designed and fabricated. Such device could automatically spray water to the main tower every ten minutes for the service purpose. By changing the original way of spraying water manually for service, it saved manpower as well as improved the work efficiency.
In the bridge site, the water flow condition of the river is rather complicated: it is in the salt water at rising tide and in fresh water at falling tide. This will cause corrosion of the bridge compoents. To solve this problem, the engineers made a special study on the anti-corrosion methods for the bridge and finally adopted a type of high-performance concrete with excellent anti-corrosion property. They also applied an anti-corrosion process called “additional current and cathode protection” for the protection of the steel pipe piles.
The successful application of the above construction techniques and methods not only improved the construction quality of the bridge, but also expedited the construction.