Application of Gujiao Cofferdam in the Construction of Pile Foundations in Deep-water and Slope Rock Condition

Gutian Creek Super Major Bridge is located in Gutian county in Fukien province and Minqing county in Fujian province to hand over boundary place,among them 7# main piers are lacated in the central Gutian construction,water depth about 43m,river bed is weak weathered standstone,without overburden and highly level off,within the scope of pile caps is terrain elevation to achieve 5m-7m,cause the steel pipe piles and casings of drilling platforms can not be inserted into the rock steadly.In addition,because of the influence of downstream Shuikou hydropower shiplock,large floating crane can not get into the area,selection of construction equipment severely limited.After the alternative schemes,decide to carry on the construction by lmmersioning the Gujiao cofferdam with Floating gantry.According to the measured data of the elevation of the river,process the steel cofferdam with high and low blade foot,and put together on Floating gantry and sink into the river,use the Floating gantry and crane sink down the steel casings,pouring underwater concrete bottom sealing,and use the steel casings to construct the drilling platforms of the main pier foundations by Floating crane.