Construction Techniques for Steel Boxed Cofferdam of Tower Pier Pile Cap of Dagu River Shipping Channel Bridge,Qingdao Bay Bridge

The Dagu River Shipping Channel Bridge of Qingdao Bay Bridge is a single tower self-anchored suspension bridge with asymmetric 4-span continuous steel box girder.The pile cap of the tower pier of the Bridge is a rounded corner octagonal structure in plan,42 m in length,23.25 m in width and 6 m in depth and the pile cap is constructed by the steel boxed cofferdam.The cofferdam is a combined single-wall and double-wall one mainly composed of the double-wall collision-proof part,single-wall part for concrete bottom sealing,single-wall breakwater board,internal supporting system,suspension system and the cofferdam is lowered in place by group jacks.The construction techniques for the cofferdam are presented herewith and the construction of the integral lowering of the cofferdam is described in detail.