Helically embedded plate anchors for floating offshore wind: potential and proof of concept

Helical anchors are a promising solution for anchoring floating offshore wind turbines, offering high holding capacity relative to their dry weight and noiseless installation. However, practical challenges associated with potentially high torque requirements coupled with their relatively poor performance under lateral loading have hampered their uptake by the offshore industry. This paper introduces the Helically Embedded PLate Anchor (HEPLA), a new anchor concept that is installed as a screw pile but loaded as a plate anchor. Installation involves rotating and pushing the follower shaft to reach a target depth, after which the shaft is detached and retrieved for subsequent installations, leaving only the helical plate embedded in the seabed. Proof-of-concept experiments conducted in a geotechnical centrifuge in overconsolidated kaolin clay show that the HEPLA concept is feasible, practical, and results in behaviour that is consistent with conventional helical anchors. The results indicate that the HEPLA has the potential to be a cost-effective and viable alternative offshore anchoring system, requiring lower installation torque than a conventional helical anchor (as the shaft can be smaller), less overall steel as the follower shaft is reused across installations, and significant resistance under non-vertical loading.