Performance of bucket foundations during installation and under sustained vertical loading

Bucket foundations in tripod- or tetrapod-jacket structures may be subjected to sustained and cyclic uplift loading; hence, their stability under uplift loading has received attention. Model tests were conducted in the present study to investigate the performance of bucket foundations under sustained loading, with the aim of determining the critical uplift load that ensures foundation stability. The first series of model tests included monotonic and sustained uplift tests with the skirt compartment vented, aiming at investigating the reconsolidation effect on the ultimate frictional resistance along the skirt. The drainage valve was sealed in the second series of tests, such that the evolution of the frictional resistance, reverse end bearing resistance, and suction on the bucket under sustained loading could be illustrated. Moreover, the critical sustained uplift loading level is recommended based on the rate of the accumulated displacement of the bucket under sustained uplift loading, providing implications for the usage of suction in design practices.