Effect of installation advancement ratio on two-way cyclic response of a single-helix screw pile for offshore wind

TY - GEN

T1 - Effect of installation advancement ratio on two-way cyclic response of a single-helix screw pile for offshore wind

AU - Wang, Wei

AU - Brown, Michael

AU - Sharif, Yaseen

AU - Davidson, Craig

AU - Ciantia, Matteo

N1 - Conference code: 5

PY - 2025

Y1 - 2025

N2 - Screw piles have been proposed as a silent and efficient type of foundations and anchors for offshore renewable energy application (e.g. floating wind). For large screw piles, conventional pitch-matched installation (advancement ratio, AR = 1.0) may be impractical due to the prohibitively high installation crowd force. By over-flighting (AR < 1), it is possible to reduce installation crowd force to zero and create pull in forces, as well as improving in-service tensile (both monotonic and cyclic) response at expense of reduced compressive response. For some applications e.g. serving as a foundation of a jacket structure, the pile may be subject to two-way cyclic loading. This study uses centrifuge tests to illustrate symmetric two-way, i.e. being in tension and compression alternatively, cyclic performance of a screw pile installed in sand, with effects of variation of advancement ratio being considered. Compared to previous one-way tensile cyclic tests, change of direction of displacement accumulation creates a more abrupt accumulation for the two-way loading cases depending on the magnitude of the load applied. The optimal AR value for two-way cyclic performance (AR = 0.5 in this study) is higher than that seen as optimal (AR = 0.25 in this study) for purely one-way tensile cyclic performance, as a balance of compressive and tensile response is needed. In all cases though, over-flighted installation it is observed to have a beneficial effect on cyclic performance.

AB - Screw piles have been proposed as a silent and efficient type of foundations and anchors for offshore renewable energy application (e.g. floating wind). For large screw piles, conventional pitch-matched installation (advancement ratio, AR = 1.0) may be impractical due to the prohibitively high installation crowd force. By over-flighting (AR < 1), it is possible to reduce installation crowd force to zero and create pull in forces, as well as improving in-service tensile (both monotonic and cyclic) response at expense of reduced compressive response. For some applications e.g. serving as a foundation of a jacket structure, the pile may be subject to two-way cyclic loading. This study uses centrifuge tests to illustrate symmetric two-way, i.e. being in tension and compression alternatively, cyclic performance of a screw pile installed in sand, with effects of variation of advancement ratio being considered. Compared to previous one-way tensile cyclic tests, change of direction of displacement accumulation creates a more abrupt accumulation for the two-way loading cases depending on the magnitude of the load applied. The optimal AR value for two-way cyclic performance (AR = 0.5 in this study) is higher than that seen as optimal (AR = 0.25 in this study) for purely one-way tensile cyclic performance, as a balance of compressive and tensile response is needed. In all cases though, over-flighted installation it is observed to have a beneficial effect on cyclic performance.

KW - screw pile

KW - helical pile

KW - cyclic loading

KW - installation effect

KW - floating wind

U2 - 10.53243/ISFOG2025-378

DO - 10.53243/ISFOG2025-378

M3 - Conference contribution

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

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

Y2 - 9 June 2025 through 13 June 2025

ER -