Bearing mechanism of innovative pile-bucket foundations for offshore photovoltaic systems in soft clay under combined loading

This study investigates the bearing behavior of a pile-bucket composite foundation in marine soft clay under combined vertical, horizontal, and moment (V-H-M) loading, with direct application to offshore photovoltaic systems deployed in shallow-water regions. Centrifuge tests and validated 3D finite element analyses employing the Nanshui constitutive model were conducted. The results indicate that the pile-bucket foundation exhibits a hybrid deformation mode, effectively integrating the deep rotational restraint of the pile with the shallow translational constraint of the bucket. Under combined V-H-M loading, the composite foundation demonstrates a significantly expanded failure envelope. Notably, the vertical load enhances the lateral capacity to a greater extent in the composite system compared to monopile or suction caisson foundations. Plastic strain analysis reveals a synergistic interaction, where the pile extends the plastic zone deeper while the bucket mobilizes a broader near-surface soil mass, leading to a more distributed and efficient load-transfer mechanism. The findings provide critical insights for the optimized design of innovative pile-bucket hybrid foundations in soft clay for offshore photovoltaic arrays.