Performance of shared suction caisson anchors in clay for floating offshore wind turbines subject to inclined cyclic loading sequences

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4. Performance of shared suction caisson anchors in clay for floating offshore wind turbines subject to inclined cyclic loading sequences

Shared suction caisson anchors have emerged as a promising solution for station-keeping of floating offshore wind turbines (FOWTs). When used with a taut mooring configuration, these anchors experience complex inclined load components and irregular cyclic loading that vary in amplitude and frequency throughout their service life. Such cyclic loads can result in cumulative vertical displacements, reducing the anchor's embedment depth and load capacity. This study employs three-dimensional (3D) finite element analysis using an advanced soil constitutive model calibrated against cyclic element tests to evaluate the performance of a suction caisson anchor in a clay deposit, under multi-directional inclined cyclic loading with varying sequences. Cyclic loading sequences were applied in ascending and descending orders to investigate their impact. The effect of the load ordering sequence is demonstrated by comparing the cyclic ratcheting, excess pore-water pressure(pwp) build-up and linking these to the global caisson response in terms of cumulative vertical and lateral displacement. Results suggest that the sequence of cyclic loading significantly impacts the caisson's performance under fully undrained conditions in clay deposits, highlighting the importance of load sequencing in design considerations.

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

11 - Suction installed foundations and anchors