3D Finite Element Modelling of Monopiles in Sand Validated against Large Scale Field Tests-Paper

Paper

Pdf Summary

The paper presents a practical method for calibrating three-dimensional finite-element models of offshore wind monopiles in sand. It uses the HSsmall soil model and derives its required soil parameters primarily from cone penetration test (CPT) data, reducing reliance on laboratory sampling and subjective engineering judgment.<br /><br />The method estimates sand strength and stiffness from CPT measurements, including relative density, friction and dilation angles, small-strain shear modulus, and the normal stiffness parameters. The authors calibrated the approach through more than 100 model simulations and compared predictions with large-scale lateral pile tests at Blessington in Ireland and Dunkirk in France. They also tested it against an independent, 4.3 m diameter pile test at Cuxhaven, Germany.<br /><br />The calibrated models closely reproduced measured load–displacement and rotation responses across a range of pile sizes, lengths, and sand conditions. Accuracy exceeded 90% on average for the Blessington and Dunkirk tests; the independent Cuxhaven comparison achieved 97%. The method also outperformed the default stiffness approach in Plaxis MoDeTo for the cases examined.<br /><br />The results suggest that relatively simple constitutive models, when carefully calibrated using in-situ data, can accurately predict the monotonic response of monopiles, including short piles that undergo near-rigid rotation. However, the correlations were developed mainly for medium-to-very-dense quartz-silica sands. The authors advise caution when applying them to loose sands or soils with substantial silt content.

Keywords

offshore wind monopiles

finite-element model calibration

HSsmall soil model

cone penetration test

sand parameters

lateral pile tests

load-displacement response

pile rotation

small-strain shear modulus

Plaxis MoDeTo