Stochastic numerical analyses to investigate the effects of the spatial nonuniformity of offshore ground on the serviceability of monopile foundations

ABSTRACTThe evidence of soil nonuniformity has been reported in several site investigation reports and is well-confirmed for any soil in general. However, studies related to the spatial soil variability of offshore ground are somewhat limited, and current design practices for monopile foundations also overlook the uncertainty of the offshore ground. This paper presents the probabilistic evaluation of the serviceability limit state of monopile foundations considering the spatial variability of offshore ground. The nonuniformity of the ground is modeled utilizing the site-specific undrained shear strength (su) as a stochastic variable, using a spatially correlated Gaussian random field. A hardening soil constitutive model is utilized in 3D finite element analysis of offshore ground, with a focus on parameter calibration. The reliability of the serviceability limit state is assessed based on the allowable load on the pile head. The stochastic behavior of the maximum bending moment and maximum shear force along the depth of the monopile is also investigated. Besides, the paper also highlights the importance of incorporating ground nonuniformity during the design process of a monopile foundation.KEYWORDS: Offshore wind turbinesmonopile foundationserviceability limit staterandom fieldundrained shear strength Disclosure statementNo potential conflict of interest was reported by the author(s).Ethics approvalNot Applicable.ConsentNot applicable.Availability of data and materialMost of it is provided in the manuscript, and the remaining is available upon request.Code availabilityAvailable on request.Open accessAuthors declare that this article is distributed under the terms of the Creative Commons Attribution Noncommercial License, which permits any non-commercial use, distribution and reproduction in any medium, provided the original author(s) and source are credited.Authors' contributionsRituraj S Sujawat: Conceptualisation, Methodology, Investigation, Data collection and analysis, Result interpretation, Writing: original draft; Ritesh Kumar: Supervision, Conceptualisation, Writing: review and editing.Additional informationFundingAuthors have received funds from Faculty Initiation Grant, FIG100915; Ministry of Education, Government of India for the financial support provided in terms of Prime Minister's Research Fellowship to the research scholars.