Lateral Loading Capacity of Jacket Foundation with Three Helical Piles for Offshore Wind Turbines

Abstract

The rapid development of offshore wind power and the need to move to deeper sea areas while reducing costs per kilowatt necessitate the employment of a new jacket and helical pile combination. This new combination combines the advantages of both jacket structures and helical piles and provides a superior bearing capacity and installation efficiency compared to conventional pile foundations. Foundations account for 25%–34% of the overall cost of construction, but the use of this new foundation would be highly significant for the further development of offshore wind power. This study presents numerical results for the horizontal bearing capacity when horizontal displacement is applied, focusing on the bearing capacity and characteristics of the helical pile jacket foundation as well as the differences between the bearing mechanisms and failure modes of normal pile and helical pile types. ABAQUS model parameters are obtained through trial calculations based on actual engineering data, and the finite element model (FEM) is validated using data from a model experiment. Subsequently, different FEMs are established, and numerical results are compared and presented. Through a comparison between a normal pile jacket foundation and a helical pile jacket foundation with different helical blade numbers, the differences in the bearing mechanisms and failure modes are revealed. The failure of the normal pile jacket foundation is instantaneous and sudden, whereas that of the helical pile foundation is incremental and accumulative. These data highlight the most significant contributions and vulnerabilities of the one-pile side of the foundation and suggest that the addition of blades on the one-pile side is the most effective way of improving the foundation’s bearing performance. In addition, the interaction between the compression side and tension side is analyzed in relation to differing the relative magnitudes of their bearing capacities.

Keywords

Offshore wind power / Helical pile jacket foundation / Helical pile / Lateral loading capacity / Failure mode

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