Investigating the monotonic behaviour of hybrid tripod suction bucket foundations for offshore wind towers in sand

Abstract

Existing tripod suction bucket foundations, utilised for offshore wind turbines, are required to resist significant lateral loads and overturning moments generated by wind and currents. This paper presents an innovative type of tripod bucket foundation, 'hybrid tripod bucket foundation', for foundations of offshore wind turbines, which has the ability to provide a larger overturning capacity compared with conventional tripod buckets. The proposed foundation consists of a conventional tripod bucket combined with three large circular mats attached to each bucket. A series of experiments were conducted on small-scale models of the proposed foundation subjected to overturning moment under 1g conditions in loose sand. Different circular mat diameter sizes with various bucket spacings were considered and the results were compared with conventional tripod bucket foundation. Finite element models of the proposed foundation were developed and validated using experimental results and were used to conduct a parametric study to understand the behaviour of the hybrid tripod bucket foundation. The results showed that there is a significant increase in overturning capacity provided by the novel foundation. The results of this work can significantly improve lowering the costs associated with installation of foundations to support offshore wind turbines.

The Horizontal Bearing Characteristics and Microscopic Soil Deformation Mechanism of Pile-Bucket Composite Foundation in Sand

“…In response to these requirements, various novel foundation designs suitable for offshore wind power were proposed. Faizi et al [1] proposed that the composite three-bucket foundation combined with a circular plate can effectively improve the foundation's anti-overturning ability and thus improve the overall bearing capacity of the structure; Zhang et al [2] employed a horizontal monotonic loading model test on hollow conical foundations under mediumcoarse sand conditions and explored the impacts of foundation dimensions and loading height on the horizontal bearing capacity, as well as the distribution patterns of soil pressure; and Bayton et al [3] experimentally determined that the deflection and bending moments of large-diameter piles calculated using API specification were lower than the measured values. Liu et al [4] focused on the influence of pile-bucket structure dimensions and penetration depth on foundation-bearing capacity and deformation by a three-dimensional finite element model.…”

Experimental Investigation on the Motion Characteristics of Air-Floating Tripod Bucket Foundation during Free Floating

“…One innovative foundation design that is currently being widely used in wind power development is the bucket foundation. There are three main types of bucket foundations used in offshore wind turbine engineering: mono-bucket foundation [3][4][5], composite bucket foundation [6,7], and multi-bucket foundations [8][9][10]. One of the main construction technologies used for composite and multi-bucket foundations is their air-floating characteristics.…”

Vertical Monotonic and Cyclic Responses of a Bucket in Over-Consolidated Clay

“…With the expansion of offshore wind energy, bucket foundations have been developed and considered as an economic option to support wind turbines [1,2]. Compared to conventional piles or large diameter mono-piles, the bucket foundations are with smaller aspect ratios and can be installed conveniently into the seabed by jacking and assisted suction [3,4].…”