Design and construction of intermediate tower´s deepwater steel boxed cofferdam concurrently used as boring platform for Maanshan Changjiang River Highway Bridge

The double-arm steel boxed cofferdam is used in the suspension bridge of left branch channels of Ma an Shan Chang Jiang River Highway Bridge´s foundation for the intermediate tower, concurrently used as boring platform. The cofferdam satisfies functions of driving and guiding of the steel casings, sup-porting of the boring platform, using as the water retaining structure during construction of the pile cap, Causing dry construction environment under water and so no. The cofferdam relies on one´s own buoyancy to floating according to the water level of construction, and which support on pile guarding-cylinder of corresponding position. The paper especially introduces the design characteristic, principle, method and construction craft of steel boxed cofferdam-platform.