Influence of scour depth and type on p–y curves for monopiles in sand under monotonic lateral loading in a geotechnical centrifuge

Journal article (2020)

Authors

G. Chortis Student
A. Askarinejad Geo-engineering - CEG
L.J. Prendergast Geo-engineering - CEG , University of Nottingham
Q. Li Geo-engineering - CEG
Kenneth Gavin Geo-engineering - CEG
Research Group
Geo-engineering (CEG) (TU Delft)
Copyright: © 2020 G. Chortis, A. Askarinejad, L.J. Prendergast, Q. Li, Kenneth Gavin
DOI
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https://doi.org/10.1016/j.oceaneng.2019.106838
Scour Centrifuge modelling P-y curves Offshore monopiles
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Published Date

2020

Language

English

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Faculty

Civil Engineering & Geosciences

Department

Geoscience and Engineering

Research Group

Geo-engineering

Abstract

The influence of scour on the lateral response of monopile foundations for offshore wind turbines is investigated in this paper. Application of lateral load-displacement (p-y) curves to predict the lateral pile behaviour is subject to uncertainty as many of the presently used design approaches have been derived for long, slender piles. These piles, with typical length/diameter ratios (L/D) of greater than 10 behave differently compared to rigid monopiles, with L/D typically less than 6. In this paper, centrifuge tests are conducted on a monopile model under various scour scenarios and p-y curves are derived from strain gauges embedded along the model pile wall. Global scour and two different shapes for local scour holes are studied. Using the piecewise polynomial method for extraction of p-y curves from sparsely distributed strain measurements, it is recommended to use a 4th order polynomial for the moment profile to extract soil reaction and a 7th order polynomial for the moment profile to calculate pile deflection. Results indicate that the pile behaviour is significantly influenced by the nature (size, shape) of the scour holes affecting the pile–soil system and suggest that the p-y curves should be appropriately modified to account for this behaviour.