Experimental research on the lowering process of the three and four-bucket jacket foundation of offshore wind turbine

Whether or not the top of the multi-bucket jacket foundation is open during the lowering process affects the air-water replacement process in the bucket. The bucket's layout impacts the skirt effect, the shielding effect under the wave load, and the force during the lowering process. For four types of multi-bucket jacket foundations, the method of the experiment is adopted to study the influence of the foundation structure type, the lowering velocity, the perforation ratio of the top, and the initial air storage in the bucket on the foundation dynamic characteristics and response mechanism during the lowering process under the two construction methods of ventilation and active air storage. During the lowering operation of the top ventilation, the air pressure response trend of the three-bucket and four-bucket jacket foundation with the same size are consistent. The effect of the lowering velocity on the air cushion height in the bucket is greater than that of the perforation ratio. During the lowering process of active air storage, before the top cover is completely submerged, the air cushion height in the bucket basically increases linearly, and is stable when it continues to be lowered, and increases slightly at the landing on the seabed stage. The dynamic amplification factor (DAF) value and failure factor of the sling during the lowering process of the four kinds of multi-bucket jacket foundations all meet the design requirement. The initial air storage in the bucket can be between 5% and 15%.