Centrifuge modelling of monopiles subjected to lateral loading

Document Type : Article


School of Civil Engineering, College of Engineering, University of Tehran, Tehran, Iran


Monopiles are the most common foundation type used for fixed-bottom substructures in offshore wind installations. In an offshore environment, the predominant load is cyclic, which affects the stiffness and deformation properties of foundation systems, especially monopiles. To investigate the effect of cyclic loading on a short (rigid) steel monopile, a set of displacement-controlled ηg laboratory tests were designed. This paper presents the procedure and results of eight centrifuge tests investigating monopile behaviour when subjected to lateral monotonic and cyclic loading. The general trend of monotonic response is in good agreement with the results of similar experimental studies, however, much softer behaviour was observed compared to the equivalent Winkler model on API p-y curves. The cyclic tests focused on the stiffness and deformation properties of a soil-pile system under fatigue loading. Increases, decreases or no changes in secant stiffness were observed depending on the regime of the applied cyclic displacements which are in contradiction to current design methodology where only cyclic degradation is assumed. Influence of load cycling on cyclic bending moments along the pile shaft was discussed and found to be of minor significance


Main Subjects

1. Leblanc, C., Houlsby, G.T., and Byrne, B.W. "Response of stiff piles in sand to long-term cyclic lateral loading", Geotechnique, 60(2), pp. 79-90 (2010).
2. Achmus, M., Abdel-Rahman, K., and Kuo, Y.S. "Behaviour of large diameter monopiles under cyclic horizontal loading", 12th International Colloquium on Structural and Geotechnical Engineering (ICSGE) Cairo, Egypt, GTE039 (2007).
3. Reese, L. and Matlock, H. "Non-dimensional solutions for laterally loaded piles with soil modulus assumed proportional to depth", In Proceedings of the 8th Texas Conference on Soil Mechanics and Foundation Engineering, Austin, TX, pp. 1-23 (1956).
4. McClelland, B. and Focht, J.J.A. "Soil modulus for laterally loaded piles", Journal of the Soil Mechanics and Foundations Division, ASCE, 82(4), pp. 1-22 (1956).
5. Reese, L.C., Cox, W.R., and Koop, F.D. "Analysis of laterally loaded piles in sand", In 6th Annual Off-shore Technology Conference: Conference Proceedings, Houston, Tex, pp. 437-483 (1974).
6. O'Neill, M.W. and Murchison, J.M. "An evaluation of p-y relationships in sands", Department of Civil Engineering, University of Houston, TX. Research Rep. No. GT-DF02-83 (1983).
7. Kallehave, D., Byrne, B., Thilsted, C.L., and Mikkelsen K.K. "Optimisation of monopiles for off- shore wind turbines", The Philosophical Transactions A of the Royal Society, 373(2035), 20140100 (2015).
8. Li, Z., Haigh, S.K., and Bolton, M.D. "Centrifuge modelling of mono-pile under cyclic lateral loads", In Proceedings of the 7th International Conference on Physical Modelling in Geotechnics (ICPMG 2010), Zurich, Switzerland, pp. 965-970 (2010).
9. Long, J. and Vanneste, G. "Effects of cyclic lateral loads on piles in sand", Journal of Geotechnical and Geoenvironmental Engineering, 120(1), pp. 225-244 (1994).
10. Lin, S.S. and Liao, J.C. "Permanent strains of piles in sand due to cyclic lateral loads", Journal of Geotechnical and Geoenvironmental Engineering, 125(9), pp. 789-802 (1999).
11. Rosquoet, F., Thorel, L., Garnier, J., et al. "Lateral cyclic loading of sand-installed piles", Soils and Foundations, 47(5), pp. 821-832 (2007).
12. Klinkvort, R.T. and Hededal, O. "Lateral response of monopile supporting an offshore wind Turbine", Proceedings of the Institution of Civil Engineers - Geotechnical Engineering, 166(2), pp. 147-158 (2013).
13. Lesny, K. and Hinz, P. "Investigation of monopile behaviour under cyclic lateral loading", In Proceeding of the 6th International Conference on Offshore Site Investigation and Geotechnics, London, pp. 383-390 (2007).
14. Achmus, M., Kuo, Y., and Abdel-Rahman, K. "Behaviour of monopile foundations under cyclic lateral load", Computers and Geotechnics, 36(5), pp. 725-735 (2009).
15. Klinkvort, R.T., Leth, C.T., and Hededal, O. "Centrifuge modelling of a laterally cyclic loaded pile", In Proceedings of the 7th International Conference on Physical Modelling in Geotechnics (ICPMG 2010), Zurich, Switzerland, pp. 959-964 (2010).
16. Rudolph, C., Bienen, B., and Grabe, J. "Effect of variation of the loading direction on the displacement accumulation of large-diameter piles under cyclic lateral loading in sand", Canadian Geotechnical Journal, 51(10), pp. 1196-1206 (2014).
17. Taylor, R.N., Geotechnical Centrifuge Technology, Blackie Academic and Professional, Glasgow, Scotland (1995).
18. Klinkvort, R.T., Hededal, O., and Springman, S.M. "Scaling issues in centrifuge modelling of monopiles", International Journal of Physical Modelling in Geotechnics, 13(2), pp. 38-49 (2013). DOI: 10.1680/ijpmg.12.00010.
19. Moradi, M. and Ghalandarzadeh, A. "A new geotechnical centrifuge at the University of Tehran, I.R. Iran", Physical Modelling in Geotechnics - Springman, Laue & Seward (Eds.), Taylor & Francis Group, London, pp. 251-254 (2010).
20. Farahmand, K., Lashkari, A., and Ghalandarzadeh, A. "Firoozkuh sand: introduction of a benchmark for geomechanical studies", Iran J Sci Technol Trans C (Civil Eng,), 40(C2), pp. 133-148 (2016).
21. Muhlhaus, H.B. and Vardoulakis, I. "The thickness of shear bands in granular materials", Geotechnique, 37(3), pp. 271-283 (1987).
22. Ovesen, N.K. "The scaling law relationships, design parameters in geotechnical engineering", In 7th ECSMFE, Brighton, 4, pp. 319-323 (1979).
23. Klinkvort, R.T. and Hededal, O. "Effect of load eccentricity and stress level on monopile support for offshore wind turbines", Canadian Geotechnical Journal, 51(9), pp. 966-974 (2014).
24. Choo, Y.W. and Kim, D. "Experimental development of the p-y relationship for large-diameter off-shore monopiles in sands: centrifuge tests", Journal of Geotechnical and Geoenvironmental Engineering, 142(1), p. 04015058 (2015).
25. Alderlieste, E.A., Dijkstra, J., and Van Tol, A.F. "Experimental investigation into pile diameter effects of laterally loaded monopiles", In Proceedings of the ASME 30th International Conference on Ocean, Offshore and Arctic Engineering (OMAE2011-50068), Rotterdam, The Netherlands, 7, pp. 985-990 (2011).
26. Remaud, D., Physical Modeling of Pile Under Lateral Loads: Interpretation Problem and of Validation, Comptes-rendus du prix jeune chercheur 99, 2 cong. Univ.de genie civil AUGC, Poitiers, France, pp. 185- 192 (1999).
27. Liu, J., Yuan, B., Mai, V.T., and Dimaano, R. "Optical measurement of sand deformation around a laterally loaded pile", Journal of Testing and Evaluation, ASTM, 39(5), pp. 1-6 (2011).
28. API (American Petroleum Institute) RP2A-WSD: Recommended Practice for Planning, Designing, and Constructing Fixed Offshore Platforms: Working Stress Design, American Petroleum Institute, Washington DC, USA (2005).
29. Jagodnik, V. and Arbanas, Z. "Testing of laterally loaded piles in natural sandy gravels", International Journal of Physical Modelling in Geotechnics, 15(4), pp. 191-208 (2015).
30. Wilson, D. "Soil-pile-superstructure interaction in liquefying sand and soft clay", Ph.D. Dissertation, University of California, Davis, CA (1998).
31. Kondner, R.L. "Hyperbolic stress-strain response: cohesive soils", Journal of the Soil Mechanics and Foundations Division, ASCE, 89(1), pp. 115-143 (1963).
32. Georgiadis, M., Anagnostopoulos, C., and Saekou, S. "Centrifugal testing of laterally loaded piles in sand", Canadian Geotechnical Journal, 29(2), pp. 208-216 (1992). DOI: 10.1139/t92-024.
33. Poulos, H. and Davis, E., Pile Foundation Analysis and Design, Rainbow- Bridge Book Co., Wiley, New York (1980).
34. Darvishi-Alamouti, S., Bahaari, M.R., and Moradi, M. "Natural frequency of offshore wind turbines on rigid and  flexible monopiles in cohesionless soils with linear stiffness distribution", Applied Ocean Research, 67, pp. 91-102 (2017).
35. Qin, H., and Dong Guo, W. "Response of static and cyclic laterally loaded rigid piles in sand", Marine Georesources and Geotechnology, 34(2), pp. 138-153 (2014).
36. Hededal, O. and Klinkvort, R.T. "A new elasto-plastic spring element for cyclic loading of piles using the p-y curve concept", In Numerical Methods in Geotechnical Engineering: NUMGE 2010, Benz and Nordal, Eds., Taylor & Francis Group, London, pp. 883-888 (2010).
37. Memarpour, M.M., Kimiaei, M., Shayanfar, M., and Khanzadi, M. "Cyclic lateral response of pile foundations in offshore platforms", Computers and Geotechnics, 42, pp. 180-192 (2012).
38. Levy, N.H., Einav, I., and Hull, T. "Cyclic shakedown of piles subjected to two-dimensional lateral loading", International Journal for Numerical and Analytical Methods in Geomechanics, 33, pp. 1339-1361 (2009).
39. Zaaijer, M.B. "Foundation modelling to assess dynamic behaviour of offshore wind turbines", Applied Ocean Research, 28(1), pp. 45-57 (2006).
40. DNV.GL "Support structures for wind turbines", STANDARD DNVGL-ST-0126 (2016).