As an important component of the national highway G15 Shenhai Expressway, the Jiajin section of G15 highway is the core of Shanghai's "One Ring, Thirteen Shots, One Vertical, One Horizontal, and Multiple Connections" highway network. It undertakes the important transportation function of connecting the western towns of Shanghai and supporting regional industrial development. The total length of the 10th section of the renovation and expansion project is about 1.68 kilometers, covering multiple key projects such as bridges, roads, and drainage. The lower structure adopts a fully prefabricated assembly of columns and cover beams, and the columns are connected to the bearing platform through grouting sleeves. The technical standards are high and the precision control is strict. However, it faces multiple challenges such as discontinuous construction sites, limited construction space near the old bridge, and cross river operations at some pier positions.
To ensure the successful lifting of the first column in one go, the project team attaches great importance to it, plans ahead and deploys carefully. From the preparation and optimization of the first piece construction plan to the specialized technical briefing of construction personnel; From the selection and verification of lifting equipment to the precise calibration of measuring instruments, every step strictly follows the requirements of the specifications and is checked layer by layer. The first column of this project has a length and width of 1.4 meters, a height of 14 meters, and a weight of approximately 66 tons. It is lifted across the river using a 350 ton crawler crane, with a boom height of 48 meters and a turning radius of 16 meters. The single machine load rate is strictly controlled within 85% to ensure safe and stable lifting.
Before construction, the project technical team analyzed the entire process of component hoisting through special meetings, tabletop simulations, and other methods. A comprehensive analysis was conducted on the complex surrounding environment and existing structures adjacent to the G15 mainline highway, river channels, and factory areas, ensuring construction safety and achieving millimeter level installation accuracy.
Before hoisting, the plane position of the old bridge should be re measured in detail, and the position of the embedded steel bars in the columns and the flatness of the bearing platform interface should be repeatedly verified. A chiseling machine should be used to chisel the bearing platform surface and the end face of the columns to ensure the bonding strength of the contact surface. During lifting, the entire process is controlled by a dedicated lifting commander, and two theodolites synchronously monitor the verticality of the columns from different directions. By adjusting the steel inserts, the axis deviation is accurately controlled, and ultimately the verticality deviation of the column installation is less than 2 millimeters, far exceeding the specification requirements. During the grouting stage, high-strength non shrinkage grouting material is used, and it is strictly mixed according to the precise mix proportion. Special grouting equipment is used to press the grout from the lower grouting hole to ensure that the grout inside the sleeve is full. After on-site testing, the compressive strength of the grouting material meets the design and specification requirements.
The successful completion of the first column hoisting not only verifies the scientific and rational construction technology of the project, but also hones a construction team with excellent technology and solid work style. Next, the project team will comprehensively summarize the experience of the first piece construction, further optimize the construction process, refine quality control measures, and use "model guidance" to promote standardization and normalization of subsequent construction. We will strive to achieve the project construction node goals, contribute the strength of the three airlines to the early opening of the G15 highway Jiajin section expansion project, and help Shanghai improve the regional transportation network, enhance road traffic capacity and service level. (Liu Shuangquan and Xue Xiaobin from the Third Navigation Bureau)