Back-analysis and insights on suction caisson self-weight penetration from Seagreen 1 offshore wind farm 

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Suction caisson jackets are a promising alternative to monopile foundations, particularly for sites with shallow bedrock and relatively large water depths. They offer benefits such as minimal penetration and quieter installation, which reduces environmental risks compared to impact-driven foundations. The success of suction caisson installations relies heavily on the behaviour during self-weight penetration (SWP). Both insufficient and excessive SWP can cause problems - insufficient penetration can lead to a loss of seal, impairing suction generation, while excessive uneven penetration among caissons can cause impermissible stresses at the jacket interface. These stresses can be especially concerning for large SWPs, as ground restraints may intensify the stress buildup. Accurate estimation of caisson behaviour during SWP is crucial to avoid costly mitigation measures or the need for caisson extraction. This paper presents a comparative analysis of SWP estimates using the cone penetration test (CPT)-based design model recommended by DNV and data from the Seagreen 1 (SG1) offshore wind farm, where 114 suction caisson jackets were installed between 2022 and 2023. The study reveals limitations in the current CPT-based model and proposes a new, more refined model to improve SWP predictions for different soil types.

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

11 - Suction installed foundations and anchors