Numerical Analysis of a Single Large-diameter Cofferdam under Offshore Loadings

—A new type of steel cofferdam for offshore structures is presented and analyzed in this paper. This new cofferdam is a single body with a large double sleeve cross-section, in contrast with the conventional one which is assembling steel sheet piles, and is filled with water inside. To evaluate its structural behaviors and safety against offshore loadings, several numerical analyses were conducted using ANSYS Mechanical. For each construction stage of the cofferdam, three-dimensional finite element models were used to simulate the cofferdam under offshore loadings including wave and wind which is corresponded to Southern-west Sea of Korea. Results show that suction and hydrostatic pressure is dominant across the board during installation. Also, earth pressure and hydrodynamic wave forces mainly affected stress increases during penetration and dewatering.