Abstract
With the rapid development of offshore wind turbines, traditional monopiles have increasingly exhibited performance limitations. In recent years, plate-monopile hybrid foundations and bucket-monopile hybrid foundations have attracted growing attention due to their structural simplicity and ease of fabrication. However, existing studies have mostly investigated these two hybrid foundation concepts independently, and systematic comparisons under comparable conditions remain lacking, particularly with respect to their soil-pile interaction behaviours. Based on the principle of equal material consumption, this study conducts a series of 1 g scaled model tests combined with prototype numerical simulations. The aim is to comparatively investigate the mechanical response differences and pile-soil interaction mechanisms among monopile, plate-monopile hybrid foundation and bucket-monopile hybrid foundation. The results indicate that: (1) Under the principle of equal material consumption, adjusting the baseplate diameter and wall embedded depth of bucket can yield an optimum configuration that provides larger bearing capacity than the plate-monopile hybrid foundation; (2) Compared to the plate-monopile hybrid foundation under identical loading amplitude, the bucket-monopile hybrid foundation shows 30% less deflections at mudline level and 60% greater cyclic stiffness across the considered parameter range; (3) With increasing number of loading cycles, an upward shift of the pivot point is observed for all hybrid foundation configurations. The bucket-monopile hybrid foundation exhibits the most notable response; (4) High loading amplitude and long-term cyclic loading amplify the ability of bucket-monopile foundation in reducing the structural bending moment and shear force. The experimental and numerical studies are expected to provide new insights into the mechanical behaviour of the hybrid pile foundations to support their optimal design.