Feasibility and Performance of Drag Embedment Anchors in Weak Rock Seabeds for Offshore Foundation Systems

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4. Feasibility and Performance of Drag Embedment Anchors in Weak Rock Seabeds for Offshore Foundation Systems

ABSTRACT: This study evaluates the feasibility of Drag Embedment Anchors (DEAs) as foundation solutions in weak rock seabeds, where installation challenges arise due to the seabeds heterogeneous nature and complex fracture characteristics. A critical aspect of mooring system design is ensuring that the Ultimate Holding Capacity (UHC) of the anchors exceeds the applied loads. Using Limit Equilibrium Analysis (LEA), a practical assessment tool was developed to estimate anchor stability based on key rock mass parameters such as Unconfined Compressive Strength (UCS) and Geological Strength Index (GSI). The analysis revealed that UHC is not uniquely determined by a fixed pair of UCS and GSI values but varies with the applied force, as, at failure, distinct volumes of resisting rock mass are engaged by failure mechanisms. Numerical results were validated against field data for pulling forces up to 2000 kN, demonstrating the tools good predictive capabilities. While the findings indicate reduced mooring stability at higher loads, such as 3000 kN, where no field tests were conducted, they offer valuable guidance for optimizing anchor selection and configuration. These insights emphasize the importance of carefully planning testing campaigns when considering such mooring systems in rocky seabeds.

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

12 - Gravity base foundations, Drag and Plate Anchors