Determination of the Peak Vertical Punch-Through Foundation Capacity of Jack-Up Vessels in a Multi-Layered Seabed

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4. Determination of the Peak Vertical Punch-Through Foundation Capacity of Jack-Up Vessels in a Multi-Layered Seabed

Wind turbine installation vessels (WTIVs) are extensively utilized in the offshore industry for their mobility, versatility, and cost-efficiency. In multi-layered soil profiles, where a strong layer overlays a weaker one, rapid leg penetration or punch-through can occur during preloading. This failure mechanism can cause substantial structural damage and result in significant downtime for the vessel. To determine the peak punch-through capacity of spudcan foundations in sand-over-clay profiles within a multi-layered seabed, the industry traditionally relies on the load-spread method as provided in ISO 19905-1:2023. An accurate determination of the load-spread factor is crucial as it can define whether the punch-through is predicted to occur or not during installation which can affect the planning and operational timing of WTIV installations and potential leg reserve issues. This study has investigated the peak punch-through capacity for a typical WTIV using 2D axisymmetric wished-in-place Finite Element Analysis (FEA) in comparison with the load spread method in ISO19905-1:2023 and a more recent approach published in SNAME Bulletin 5-7 J-REG JIP. Throughout the study the main variables affecting the peak punch-through capacity have been identified and a parametric study has been carried out to evaluate the impact of each variable. The study compares the abovementioned methodologies with real site data and illustrates which methods can potentially overestimate the onset of punch-through capacity.

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

14 - Spudcans: penetration, extraction, interactions