Seismic response of tripod suction bucket foundation for offshore wind turbine in sands

Tripod suction bucket foundation is increasingly used to support offshore wind turbines (OWTs) due to its convenient and low-cost installation and high overturning resistance. However, the seismic response charac-teristics of OWTs of tripod bucket foundations in sands is not well covered in the literature. Therefore, this study investigates the response of tripod bucket foundations installed in sands and subjected to seismic loads employing advanced three-dimensional finite difference analysis. The variation of pore pressure around suction bucket is evaluated, and the failure mechanism of the tripod bucket foundation in sands is revealed. In addition, the displacement response of the tower, and the acceleration amplification effect of the OWT system are elucidated. It is found that the earthquake magnitude, and sand relative density and liquefaction greatly affect the foundation seismic behavior. The results revealed that the overall rotation of the tripod bucket foundation is primarily due to progressively increasing differential vertical settlement between the foundation sides of 'single bucket' and 'double bucket' associated with loading direction. It was also found that the sand liquefaction under strong shaking may lead to excessive rotation of the foundation that exceeds the service limit state. The findings from this study can provide guidance for the design of OWT tripod bucket foundations in sands.