China News Service, Jiaxing, October 20 (Fu Feiyang) On October 20, the Hangzhou Bay Cross-sea Railway Bridge, the world's longest cross-sea railway bridge, made significant progress. At 10:58 that day, at the construction site 570 meters offshore on the Haiyan side of the Hangzhou Bay Cross-Sea Railway Bridge, the last welding seam of the mid-span closure section was completed, marking the successful closure of the north channel bridge of the Hangzhou Bay Cross-Sea Railway Bridge, and the construction of the bridge entered the sprint stage of the main project.
The Hangzhou Bay Cross-sea Railway Bridge is a control project for the new Nantong to Ningbo high-speed railway (referred to as Tong-Ningbo High-speed Railway). It is located upstream of the existing Hangzhou Bay Cross-sea Highway Bridge, starting from Haiyan, Jiaxing, Zhejiang, in the north, to Cixi, Ningbo, in the south. It has a total length of 29.2 kilometers, a design speed of 350 kilometers per hour, and a double-track ballastless track design. The bridge consists of three channel bridges in the north, middle and south, as well as an approach bridge in the shoal area and an approach bridge in the sea. It is currently the longest cluster-type cross-sea railway bridge in the world with the highest construction standards under construction.
On October 20, the steel girder closing event of the Hangzhou Bay Cross-sea Railway Bridge North Channel Bridge was held. Photo by Fu Feiyang
The North Channel Bridge in Helong adopts a steel box-steel truss composite beam cable-stayed bridge structure, with a total length of 932.7 meters and a main span of 450 meters. It is the world's largest span high-speed railway ballastless track bridge currently under construction.
Prior to this, most of the ballastless track bridges for high-speed railways built in China have a span of more than 300 meters. A span of 450 meters is a new technical challenge. It is essentially a systematic project to accurately control the deformation of a large-span flexible bridge structure within the millimeter-level deviation allowed by high-precision track systems. Engineering design and construction have changed from the traditional "separate control of bridge construction and track laying" to the complex "line and bridge integration" collaborative control.
In response to complex sea conditions and construction problems of ultra-long-span steel box-steel truss composite beams, the construction team of China Railway Bridge Bureau collaborated with professional teams such as China Railway Design Group Co., Ltd., the National Key Laboratory of Bridge Intelligence and Green Construction, Southwest Jiaotong University, and the Bridge Science Research Institute to form a complete set of construction technologies of "side-span push-up, mid-span cantilevering, box first and then truss, and staggered erection".
The last steel box girder section of this closure is 9.6 meters long and weighs 123.6 tons in total. Two girder erecting cranes are used to lift it. During the construction, the construction team first conducted 48 hours of continuous observation of the cantilever beam ends on both sides to comprehensively analyze the impact and changing patterns of environmental factors on the structural stress, stay cable forces, and the spatial relationship between the Helongkou. During the day, the Helong section was lifted into the preset Helongkou space. During the night when the temperature was stable, the Helong section was accurately aligned, temporarily locked, and welded. Subsequently, the steel truss members were assembled and the cable force was adjusted.
Hangzhou Bay is one of the world's three strongest tidal bays. Strong winds, strong tides, rapids and other factors are intertwined in the bridge site area. The steel beams are also faced with multiple risks such as high-altitude operations, maritime transportation, double-machine lifting and night welding. The construction team implements safety penetration management, divides key processes such as high-altitude lifting, water vessels, and limited space welding into responsible units, and strictly implements work systems such as safety condition confirmation, one crane, one plan, and key process control.
It is reported that the South Channel Bridge has been closed on October 17. After the North Channel Bridge is closed, the two north and south channel bridges will undergo bridge deck attachment and ballastless track construction. The Middle Channel Bridge is undergoing steel girder erection construction and is expected to be closed by the end of November this year.
"As of now, the overall construction progress of the Hangzhou Bay Cross-sea Railway Bridge exceeds 90%, and it is accelerating from large-scale main structure construction to the main finishing and bridge deck system construction stages." said Luo Yunfeng, commander of the Hangzhou Bay Cross-sea Railway Bridge Headquarters of Shanghai State Railway Engineering Construction Management Co., Ltd.
The Tongning-Ningbo high-speed railway is an important part of the coastal corridor of China's "eight vertical and eight horizontal" high-speed railway network. It is constructed and managed by Shanghai State Railway Construction and Management Company and controlled and invested by Zhejiang Provincial Communications Group.
After the Tongning-Ningbo High-speed Railway is completed and put into operation, it will end the history of Haiyan and Cixi not being connected by high-speed rail. It will be connected to Yantong High-speed Railway, Shanghai-Kunming High-speed Railway, Ningbo-Taiwan-Wenzhou Railway and other lines. It is of great significance for creating the "Yangtze River Delta on the track", improving the structural layout of the regional road network, facilitating travel for people along the line, and promoting the integrated high-quality development of the Yangtze River Delta. (over)
