NANNING, Oct. 6 (Xinhua) -- A 32.6-meter-long, nearly 740-tonne double-track box girder was smoothly installed on the piers of the Songbailing Bridge on Tuesday, marking the entry of Section 1 of the Guangxi section of the Hezhan High-speed Railway into the full-scale girder erection stage, according to China Railway 25th Bureau Group Co., Ltd.
Section 1 of the Guangxi section includes nine bridges, the fabrication, transport and erection of 461 box girders, as well as subsequent track-laying work in the Guangxi section. The Songbailing Bridge requires the erection of 10 box girders, with construction facing challenges such as frequent switching between single- and double-track conditions and multiple overpasses and underpasses.
According to Zhang Jicheng, a site manager of China Railway 25th Bureau, the girder-launching machine had to pass under five portal piers while being transported to the first erection point of the section. After partial disassembly, only a 10-cm clearance remained at the top, making the operation highly difficult. The project's technical team used BIM 3D modeling to simulate special working conditions and eliminate safety interference from surrounding entities during dynamic construction. It also adopted an artificial intelligence dual monitoring platform featuring "local interlocking protection plus cloud-based remote control" to ensure safety control throughout the processes of transport, girder erection and span passing. With intelligent control, multi-dimensional early warnings can be issued for outrigger force, overall machine posture, lifting load and distance perception, effectively reducing girder erection risks.
The Songbailing Bridge is located in a coastal soft-soil section with a thick silty sand layer, where pile foundations are prone to hole collapse. The project team optimized the pile foundation drilling process, adjusted the selection of drilling equipment and drilling parameters according to geological conditions, and gave priority to reverse circulation drilling rigs to ensure the quality of pile foundations. In response to the high-salt, high-humidity and salt-fog coastal environment, the team optimized the concrete mix ratio to inhibit chloride ion penetration, applied anti-corrosion treatment to steel bars and steel components, and used a water molecule curing film to strengthen concrete curing control, enhancing the durability of the bridge structure.
The Hezhan High-speed Railway has a main line of about 139 km and a designed speed of 350 km/h. It is an important part of the Baotou (Yinchuan)-Haikou corridor and the coastal corridor in China's "eight vertical and eight horizontal" high-speed railway network. The project is expected to be completed and open to traffic in 2028, which will further expand the railway transport capacity along the coast of Guangxi and is of great significance for optimizing and improving the regional railway network layout and promoting the construction of the Beibu Gulf urban agglomeration.
