Deep-water Bridge Pile Foundation Steel Boxed Cofferdam Construction Technology Research

In recent years, with the booming development of highway construction in China, the extra large bridges are constantly emerging across the rivers, the gulfs, the straits etc. The higher request is put forward in construction of the deep-water bridge pile foundation. At present, the waterproof structures of deep-water bridges pile foundation are main steel sheet pile cofferdam, steel cofferdam, steel boxed cofferdam and so on, in those methods, the steel hanging box as the waterproof cofferdam has been widely applied in deep-water bridges pile foundation construction because of its short construction period, without sinking into the riverbed, with less material, economic rationality etc. In this paper, Based on Ankang to Shaanxi and Sichuan boundary expressway, Han-Jiang extra large bridge pile foundation construction steel boxed cofferdam in Ziyang, and through the summary of construction process and the analysis of monitoring stress and data in the steel hanging box construction, the conclusions are listed as follows:1. The influence factors of cofferdams structure selection. The hydrological, geological conditions and bridge the area of meteorology of job site. Combined with the specific engineering characteristics and requirements of the construction period, at eh same time, the mechanical equipment of construction site should be considered to select and determining the appropriate cofferdam structure.2. Steel boxed cofferdam for the construction process of the hanging box include steel integral lifting, the assembly of steel hanging box points down and the whole day block down two contents. The site condition, the construction equipment, the resource requirements and project risk factors need to be considered when choosing construction techniques.3. Monitoring steel boxed cofferdam construction process which included steel hanging box assembles, lowering, bottom sealing concrete casting with steel-string type strain gauge, analyzing stress variation in the steel boxed cofferdam construction stage, confirming the most unfavorable deformation of the steel boxed cofferdam, and providing a theoretical and practical basis for steel boxed cofferdam in the design and construction.