Construction techniques for launching of steel cofferdam of Wangdong Changjiang River Highway Bridge

The main bridge of Wangdong Changjiang River Highway Bridge in Chizhou City, Anhui Province is a steel and concrete composite girder cable-stayed bridge with span arrangement (78+228+638+228+78) m and the main girder is of the separated double boxes of the Pasco-Kenneiwick Bridge type. The foundation for the south pylon pier of the bridge is the one of bored piles and elevated pile cap and is constructed by the irregular double-wall steel cofferdam with unequal height cutting edges. The cofferdam is 50.4 m long, 28.4 m wide and weighs about 1 532 t. In accordance with the construction conditions of the foundation for the pylon pier, the construction scheme adopted for the foundation was that the cofferdam was launched to the river by the air bag method, the cofferdam with no bottom was arranged at the pier site first and the boring inside the cofferdam was carried out then. The cofferdam was fabricated in blocks and assembled horizontally in the shipyard and was launched to the river by the rubber air bag method. In the launching of the cofferdam, the launching speed of the cofferdam was controlled, using the reverse hauling from the ground anchors, winches and pulley blocks. The cofferdam was floated to the pier site by the tug boats and at this stage, the construction of the cofferdam in water was to be finally completed. ©, 2014, Wuhan Bridge Research Institute. All right reserved.