Effect of Wing Plates on Vertical Load Capacity of a Multiline Ring Anchor System in Clay
Publication: Geo-Congress 2022
ABSTRACT
Development of offshore wind in deeper waters that are beyond the feasible range of fixed towers requires a cost-effective anchorage for floating offshore wind turbines (FOWTs). The multiline ring anchor (MRA) system has been devised as a cost-effective anchor for FOWTs, by virtue of its high efficiency, its capability for securing multiple mooring lines, and its adaptability to a wide range of seabed conditions. Taut mooring systems become increasingly attractive as water depth increases, leading to combined horizontal–vertical loading on the anchor. Since the MRA is deeply embedded in the seabed, it has capabilities for resisting the vertical component of the forces imposed by taut moorings. Since the MRA lacks the reverse end bearing resistance of a conventional suction anchor, its design requires careful attention to ensure that it can resist the vertical load demand from a taut mooring. Previous preliminary studies show that the uplift resistance of the MRA in soft clay can be improved by attaching wing plates, increasing anchor size, or installing in deeper depth, the latter being limited by the constraints of suction installation. Wing plates turn out to be a very promising option, but more reliable studies of their performance are needed to support an optimally designed, cost-effective anchor. Thus, rigorous three-dimensional finite element analyses were conducted to understand how wing plates improve the uplift resistance and provide reliable evaluations of the vertical load capacity of the MRA. The results show that the soil-anchor adhesion factor, the total number of wing plates, and the width of wing plates are important factors contributing to anchor uplift resistance. To investigate an optimal design of the wing plates, a comparative study was carried out to compare the effects of wing plates on minimizing capital costs. The studies show that attaching wing plates can be an economical solution for improving axial capacity.
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Geo-Congress 2022
Pages: 59 - 68
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Published online: Mar 17, 2022
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