Key Technology for Construction of Steel-concrete Composite Suspending Cofferdam without Bottom Cover for Platform of Coastal Intercommunication Project

Abstract

Many bridge piers were built in the Coastal Interconnection Project of the Ningbo Section of the Hangzhou-Ningbo Expressway Double Line. Affected by the tides at the bridge site, the high pile caps are constructed using a suspending cofferdam without a bottom cover. Based on the consideration of various factors such as construction difficulty, safety, cost and construction period, etc. A cement structure is generally adopted as the floor of the suspended box cofferdam. The steel-concrete combined hanging box cofferdam without bottom cover adopts the structure of steel wall plate and prefabricated cement floor, and the partition wall plates are connected by bolts. The steel-concrete composite suspending cofferdam adopts the prefabricated bottom plate and wall plate. The construction sequence is listed as follows: First, weld the load-bearing corbel on the steel casing, and then hoist the prefabricated bottom plate to the steel casing corbel in blocks. Pour the wet joint between the prefabricated bottom plate and install the side plate. After that, pour the cushion after welding the shear plate. Finally, carry out the construction of the cap. During the construction of the project, the connection method between the wall plate and the bottom plate was optimized. The connection of the fine-rolled rebar hanger rod was changed to the steel bar pair pulling, which improved the construction efficiency significantly.