A CPT-based multi-spring model for lateral monopile analysis under SLS conditions in sand

Tott-Buswell, Jacques; Prendergast, Luke J.; Gavin, Kenneth

Abstract

Monopiles are the most common Offshore Wind Turbine (OWT) foundations due to their simplicity in design, fabrication, and installation. However, large new-generation turbines have led to significant changes in monopile dimensions, necessitating extensive finite element analyses and ground investigations to meet design requirements. While Cone Penetration Test (CPT)-based p - y methods can analyse slender pile lateral behaviour, they often miss additional resistance mechanisms relevant to rigid monopiles. This paper introduces CPT-informed resistance mechanisms for monopiles to incorporate additional lateral resistances beyond p - y modelling capabilities. Distributed moment–rotation ( m - θ ) springs are defined by repurposing CPT-based axial capacity estimation methods for piles; and pile tip shear and moment springs are informed by approximating a residual bearing stress post-installation using local CPT q c values. The performance of the multi-spring model is appraised against data reported from monotonic pile pushover tests conducted at two sand sites. Results show that the multi-spring model is capable of predicting pile head deflections reasonably well within serviceability deflection limits against the reported test data, but ultimate failure loads cannot be predicted using the proposed model. A clear sensitivity in pile response to local variations in CPT q c is demonstrated.

Citation

Tott-Buswell, J., Prendergast, L. J., & Gavin, K. (2024). A CPT-based multi-spring model for lateral monopile analysis under SLS conditions in sand. Ocean Engineering, 293, Article 116642. https://doi.org/10.1016/j.oceaneng.2023.116642

• Journal Article Type: Article
• Acceptance Date: Dec 30, 2023
• Online Publication Date: Jan 6, 2024
• Publication Date: Feb 1, 2024
• Deposit Date: Jan 8, 2024
• Publicly Available Date: Jan 10, 2024
• Journal: Ocean Engineering
• Print ISSN: 0029-8018
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 293
• Article Number: 116642
• DOI: https://doi.org/10.1016/j.oceaneng.2023.116642
• Keywords: In-situ testing, Numerical modelling, Offshore engineering, Piles & piling, Soil–structure interaction
• Public URL: https://nottingham-repository.worktribe.com/output/29542084
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0029801823030263?via%3Dihub