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

TY - GEN

T1 - Helically embedded plate anchors for floating offshore wind

T2 - 5TH INTERNATIONAL SYMPOSIUM ON FRONTIERS IN OFFSHORE GEOTECHNICS 2025

AU - Hidayat, W

AU - Nieiedt, Juliano

AU - O’Loughlin, Conleth D.

AU - Watson, Phil

AU - Gaudin, Christophe

AU - Bertalot, Danielle

AU - Rattley, Mike

AU - Whyte, Scott

AU - Brown, Michael

N1 - Conference code: 5

PY - 2025/6/9

Y1 - 2025/6/9

N2 - 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.

AB - 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.

KW - Screw anchor

KW - floating offshore wind turbine (FOWT)

KW - Sand

KW - plate anchors

KW - helical anchors

KW - embedded mooring chain

KW - centrifuge modelling

U2 - 10.53243/ISFOG2025-211

DO - 10.53243/ISFOG2025-211

M3 - Conference contribution

SN - 9782857827580

BT - Proceedings of the 5TH INTERNATIONAL SYMPOSIUM ON FRONTIERS IN OFFSHORE GEOTECHNICS

A2 - Abadie, C. N.

A2 - Li, Z.

A2 - Blanc, M.

A2 - Thorel, L.

PB - International Society for Soil Mechanics and Geotechnical Engineering

Y2 - 9 June 2025 through 13 June 2025

ER -