March 10, the first pile foundation of Hangzhou Bay Sea-Crossing Railway Bridge in Nantong-Ningbo high-speed rail was drilled, marking the official start of the world's longest Sea-Crossing High-Speed Railway Bridge.
Hangzhou Bay Sea-Crossing Railway Bridge is constructed by Shanghai-Hangzhou Passenger Dedicated Company, China Railway and China Railway Bridge Institute, China Consultative Management Supervision, China Railway Bridge Bureau and other units. It is a control project of the high-speed rail from Nantong to Ningbo, with a design speed of 350 kilometers per hour and a total length of 29.2 kilometers. There are three channel bridges in the north, middle and south, and approaches across embankments, sea and shoals. It is a super-long high-speed railway bridge cluster project, of which the main span of the North Channel Bridge is 450 meters, which is the world's largest span ballastless track cable-stayed bridge; the main span of the Middle Channel Bridge is 2 × 448 meters, which is the world's largest span ballastless track three-tower cable-stayed bridge.
"The whole bridge is designed according to ballastless track.". The train runs at a speed of 350 kilometers per hour. If the track is slightly uneven, it will affect the ride comfort. Therefore, the ballastless track requires a very high alignment of large-span bridges. The accuracy of bridge construction needs to be controlled at the millimeter level. The design and construction technology is very difficult. Qian Liping, commander of Hangzhou Bay Sea-Crossing Railway Bridge Command of Shanghai-Hangzhou Passenger Dedicated Company, said.
At present, the largest span of ballastless track bridges built in China is only 300 meters, and the largest main span of Hangzhou Bay Sea-Crossing Railway Bridge is 450 meters. The sea conditions are very complex, coupled with the high speed of trains, the bridge needs large stiffness and small deformation to ensure the safety, stability and comfort of high-speed trains. Faced with the challenge, the design unit has carried out a lot of calculation and research work on the structural system, and adopted a series of innovative designs, such as longitudinal fixation of the middle tower and longitudinal elastic restraint of the side tower, to reduce the displacement and deformation of the main girder, increase the stiffness of the bridge, and improve the stability and comfort of the train.
Hangzhou Bay is one of the three largest tidal bays in the world, with wide sea area, strong wind, high waves, large tidal range and rapid flow. The construction conditions of the bridge are greatly affected by the natural environment such as hydrology, meteorology and geology. The tidal range of Qiantang Tide Bay, the "wonder of the world", is up to 9 meters, and the flow rate is very fast. In addition, the sediment layer at the bottom of Hangzhou Bay is thick, the texture is soft, and the water depth is shallow. When the North Channel Bridge is at low tide level, the water depth is only about 2 meters, which will lead to the situation that large ships are easy to run aground and small ships are unstable.
"This is a world-class offshore project, which requires a large number of large-scale machinery and equipment and engineering ships. Affected by hydrological and meteorological conditions, the effective operation time is short, the construction organization is difficult and the safety risk is high.". In addition, the bridge crosses the marine ecological red line area of the Qiantang River Estuary, and in order to protect fish migration channels and bird resources, the requirements for ecological and environmental protection are also very high. Xu Bingfa, Secretary of the Party and Labor Committee of Hangzhou Bay Sea-Crossing Railway Bridge Project of China Railway Bridge Bureau, introduced.
In order to solve the problem of bridge construction, China Railway Bridge Bureau has set up a special scientific research team. The construction technology of 160-meter-deep large-diameter bored piles in the strong tidal bore area, the construction technology of embedded large-diameter super-long inclined steel piles in the strong tidal bore and high-velocity sea area, the rapid installation and removal construction technology of embedded bearing platform cofferdam in the strong tidal bore and high-velocity sea area, the prefabrication and erection technology of 80-meter-long prestressed concrete beams, the safety risk monitoring technology of offshore construction, and the platform avoidance technology of large ships. The linear construction control technology of large-span ballastless track steel girder based on digital twin and the construction measurement technology of track fine adjustment are studied, which can not only solve the construction problems of large-span ballastless track bridges in complex environment, but also provide reliable experience for the construction of high-speed railway bridges in the future.
Nantong-Ningbo high-speed rail Line starts from Nantong West Station of Yancheng-Nantong high-speed rail, passes through Suzhou City of Jiangsu Province, Jiaxing City of Zhejiang Province and Ningbo City to the south, and is introduced into Ningbo Station of Ningbo Hub. The new line is 301 kilometers long, with a design speed of 350 kilometers per hour and a construction period of 5 years. There are 10 stations in the whole line, including Nantong West, Zhangjiagang, Changshu West, Suzhou North, Suzhou South, Jiashan North, Jiaxing South, Haiyan, Cixi and Zhuangqiao, of which 5 stations in Changshu West, Suzhou South, Jiashan North, Haiyan and Cixi are new stations, and the rest are existing stations. The high-speed rail
from Nantong to Ningbo is an important part of the coastal corridor of the "eight vertical and eight horizontal" high-speed railway network in China, and its position is very important. After the completion of the project, it will be connected with the Yancheng-Nantong high-speed rail, the Beijing-Shanghai high-speed rail, the Shanghai-Kunming high-speed rail, the Ningbo-Taizhou-Wenzhou high-speed rail, the Jinhua-Ningbo Railway under construction, and the Jiangsu-South Intercity Railway along the Yangtze River, so as to promote the improvement of the road network structure in the Yangtze River Delta region, greatly facilitate the travel of the people along the line, and promote the high-quality integration of the Yangtze River Delta. It is of great significance.
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