Dynamic response of single-bucket foundation in clay under vertical variable amplitude cyclic loadings

The application of multi-bucket foundation has an increasing trend in deeper water. The horizontal dynamic response of multi-bucket foundation mainly depends on the vertical cyclic behavior of single bucket in this multibucket foundation. In order to investigate the vertical dynamic response of single bucket foundation, a series of 1g model tests were carried out under vertical cyclic loadings in over-consolidated clay. Test results show that the vertical displacement of model bucket increases and the stiffness of bucket-soil decreases with the increase of cyclic loading level parameter zeta b, which is defined as the ratio of maximum force in loading cycle and static ultimate capacity. The vertical capacity increased by about 23% and 19.5% after constant amplitude unidirectional loading and variable amplitude loading, respectively. And the vertical capacity remains unchanged after constant amplitude bi-directional loading. The vertical displacement and stiffness of bucket-soil increase with the increase of cyclic times N. Superposition theory was applied to express the vertical displacement and stiffness of bucket-soil under vertical variable amplitude cyclic tests. The stiffness law was also analyzed using the spring model. The study on the vertical behavior of single-bucket foundation can provide some reference for the design of multi-bucket foundation.