Skip to main content

Research Repository

Advanced Search

Centrifuge modeling of the impact of local and global scour erosion on the monotonic lateral response of a monopile in sand

Li, Qiang; Prendergast, L. J.; Askarinejad, A.; Chortis, G.; Gavin, K.

Centrifuge modeling of the impact of local and global scour erosion on the monotonic lateral response of a monopile in sand Thumbnail


Qiang Li

A. Askarinejad

G. Chortis

K. Gavin


Copyright © 2020 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. The majority of offshore wind turbines are founded on large-diameter, open-ended steel monopiles. Monopiles must resist lateral loads and overturning moments because of environmental (wind and wave) actions, whereas vertical loads tend to be comparatively small. Recent developments in turbine sizes and increases in hub heights have resulted in pile diameters increasing rapidly, whereas the embedment length to diameter ratio (L/D) is reducing. Soil erosion around piles, termed scour, changes the soil strength and stiffness properties and affects the system's load resistance characteristics. In practice, design scour depths of up to 1.3D are routinely assumed during the turbine lifetime; however, the impact on monopiles with low L/D is not yet fully understood. In this article, centrifuge tests are performed to assess the effect of scour on the performance of piles with low L/D. In particular, the effect of combined loads, scour type (global, local), and depth are considered. A loading system is developed that enables application of realistic load eccentricity and combined vertical, horizontal, and moment loading at the seabed level. An instrumented 1.8-m-diameter pile with L/D = 5 is used. A friction-reducing ball-type connection is designed to transfer lateral loads to the pile without inducing any rotational pile-head constraint, which is associated with loading rigs in tests of this nature. Results suggest that vertical and lateral load interaction is minimal. Scour has a significant impact on the lateral load-bearing capacity and stiffness of the pile, leads to increases in bending moment magnitude along the pile shaft, and lowers the location of peak pile bending moment. The response varies with scour type, with global scour resulting in larger moments than local scour. The size of the local scour hole is found to have a significant impact on the pile response, suggesting that scour hole width should be explicitly considered in design.

Journal Article Type Article
Acceptance Date Oct 23, 2019
Online Publication Date Jan 10, 2020
Publication Date Jan 10, 2020
Deposit Date Nov 28, 2019
Publicly Available Date Jan 11, 2021
Journal Geotechnical Testing Journal
Print ISSN 0149-6115
Electronic ISSN 0149-6115
Publisher ASTM International
Peer Reviewed Peer Reviewed
Volume 43
Issue 5
Pages 20180322
Keywords Geotechnical Engineering and Engineering Geology
Public URL
Publisher URL


You might also like

Downloadable Citations