Abstract:

To investigate the cyclic bearing behavior of suction caisson foundations subjected to cyclic loads—such as those from wind, waves, and currents—under local scour conditions in marine environments, model tests were conducted under both unscoured and locally scoured conditions. In addition, a numerical model was developed to simulate the static and cyclic loading of full-scale suction caisson foundations and to verify its reliability. Failure modes, angular displacements, and stiffness variations of the foundations were analyzed before and after local scour, as well as changes in bearing capacity before and after cyclic loading. The results indicate that the cyclic response of the foundation to horizontal loads under local scour is similar to that under unscoured conditions. However, the reduction in bearing capacity is more significant under local scour. At full scale, the suction caisson foundation demonstrates a “self-repairing” behavior under cyclic loading. Both the load amplitude ratio and the load symmetry ratio are positively correlated with the cumulative angle of rotation and negatively correlated with cyclic stiffness, which gradually decreases as the scour rate increases.

Key words: suction caisson foundation, local scour, sand, bearing characteristics, cyclic loading