Gravity Based Foundation

Scour and design optimisation

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Abstract

Within Royal HaskoningDHV an innovative concept is thought to be feasible as a new foundation for larger wind turbines in deeper waters. In this thesis the development of this innovative offshore wind turbine foundation was aided. The research focused on two topics: - Scour at this gravity based foundations. - Possible design optimisations with respect to shape and dimensions of the structure. A numerical tool was developed that is able to calculate the hydrodynamic loads on multiple configurations of this foundation. This tool uses Stokes 5th order wave theory and Morison’s equation. It was extended with analytical geotechnical stability calculations, to compare the stability of different foundations. Furthermore, a literature study was conducted to determine whether or not scour protection should be applied at the foundation concepts. It was concluded that no accurate scour depth could be predicted with the currently available methods. Therefore a computational fluid dynamics model, FinLab, was employed to determine the relative scour potential at the foundation. Moreover, a new numerical scour depth prediction method is proposed in this thesis, which is especially suitable for unconventional foundation structures.