Suction-Driven Installation of a 20 m-Diameter Circular Steel Cofferdam: A Full-Scale Field Test in Jebudo, Republic of Korea

Cofferdams provide dry, stable working conditions for construction in marine environments. However, conventional methods often require significant time and cost for installation and removal, and are prone to leakage. This study proposes a novel method for the rapid and efficient construction of a large-diameter circular cofferdam using suction-driven installation and extraction. As opposed to conventional suction bucket foundations, the upper part of the cofferdam remains exposed above the water surface, and several prefabricated segments are assembled to form a single suction unit. A full-scale field test was conducted in Jebudo, Republic of Korea, using a 20 m-diameter, 13 m-high circular steel cofferdam. The test program included the design and fabrication of a suction cover and an optimized piping system. The key measurements during installation included the suction pressure variation with the penetration depth, leakage at the segmental joints, structural deformations, and inclination. The cofferdam successfully penetrated to a target embedment depth of 5 m at an average rate of 1.83 m/h and was safely removed using reverse suction. Although suction technology has been widely applied to offshore foundations and anchors, this study is the first to demonstrate its feasibility for large cofferdams. These results provide a foundation for future offshore applications of suction-driven cofferdam installations.