Experimental and numerical investigation of the effect of vertical loading on the lateral behaviour of monopiles in sand

Q. Li, K. G. Gavin, A. Askarinejad, L. J. Prendergast*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

7 Citations (Scopus)
31 Downloads (Pure)


The influence of combined loading on the response of monopiles used to support offshore wind turbines (OWTs) is investigated in this paper. In current practice, resistance of monopiles to vertical and lateral loading is considered separately. As OWT size has increased, the slenderness ratio (pile length, L, normalised by diameter, D) has decreased and foundations are tending towards intermediate footings with geometries between those of piles and shallow foundations. Whilst load interaction effects are not significant for slender piles, they are critical for shallow footings. Previous research on pile load interaction has resulted in conflicting findings, potentially arising from variations in boundary conditions and pile slenderness. In this study, monotonic lateral load tests were conducted in a geotechnical centrifuge on vertically loaded monopiles in dense sand. Results indicate that for piles with L/D = 5, increasing vertical loading improved pile initial stiffness and lateral capacity. A similar trend was observed for piles with L/D = 3, when vertical loading was below 45% of the pile’s ultimate vertical capacity. For higher vertical loads considered, results tended towards the behaviour observed for shallow footings. Numerical analyses conducted show that changes in mean effective stress are potentially responsible for the observed behaviour.

Original languageEnglish
Pages (from-to)652-666
Number of pages15
JournalCanadian Geotechnical Journal
Issue number5
Publication statusPublished - 2022

Bibliographical note

Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care
Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.


  • centrifuge modelling
  • combined loading
  • lateral soil resistance – displacement (p–y) curves
  • monopiles
  • sand


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