The performance of shared suction caisson anchors in sand for FOWT with taut mooring

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4. The performance of shared suction caisson anchors in sand for FOWT with taut mooring

ABSTRACT:  Floating offshore wind (FOW) arrays installed with shared anchors have been proposed as a cost reduction strategy for energy production. However, the ability of shared anchors to maintain station keeping under multidirectional cyclic loading remains uncertain, leading to over-conservative design. This study investigates the performance of a shared suction caisson anchor for a FOW array subjected to multidirectional cyclic loading. Mooring loads were derived from aerohydrodynamic modelling of the IEA 15MW turbine and VolturnUS-S reference platform in an extreme sea state, with taut mooring in different water depths. A fully-coupled nonlinear dynamic finite element (FE) analysis of the anchor was carried out using the advanced Sanisand-MS constitutive model, and the performance of the shared anchor was explored. The results show that shared suction caisson anchors, when installed within a sand deposit and subjected to taut mooring loads, can maintain performance during peak 50-year return period environmental loading events. The shared anchor appears to provide a sufficient vertical tensile capacity under drained conditions. While progressive upward ratcheting behaviour of the caisson, sufficient to deteriorate anchor performance, is considered unlikely over the service lifetime of the anchor, further investigation is required. Mooring design to reduce the load inclination angle on the anchor could help alleviate this potential risk.

5th International Symposium on Frontiers in Offshore Geotechnics (ISFOG2025)

11 - Suction installed foundations and anchors