Investigation of the load-bearing capacity of suction caissons used for offshore wind turbines

• Published in: Applied ocean research 2017-09, Vol.67, p.148-161
• Main Authors: Bagheri, Pouyan, Son, Su Won, Kim, Jin Man
• Format: Article
• Language: English
• Subjects: Bearing capacity; Caissons; Centrifuges; Densification; Displacement; Field tests; Modelling; Numerical analysis; Offshore; Offshore operations; Offshore wind turbine; Rotation; Sand; Sandy soils; Soil; Soil properties; Suction bucket foundation; Turbine engines; Turbines; Wind power
• ISSN: 0141-1187; 1879-1549
• DOI: 10.1016/j.apor.2017.07.002

•Preliminary design equations and figures for bucket foundations are proposed.•Presenting normalized equations and figures for bucket foundations using Power law.•Bucket rotation and displacement are highly dependent on the bucket geometry.•Maximum stresses are seen near the bucket tip at the right inside of the bucket.•The largest soil displacement occurs near the lid inside of the bucket. This paper presents the results of three-dimensional finite element analyses of the suction bucket foundation used for offshore wind turbines. The behavior of the bucket and the response of soil supporting the bucket in dense and medium dense sandy soils subjected to static horizontal load are investigated. Field tests results and a centrifuge model test are used to validate the numerical model. Dimensionless horizontal load-displacement and overturning moment-rotation relationships are derived utilizing the Power law and Buckingham’s theorem. The results show good agreement between the numerical analysis results and the straight lines obtained from the Power law until a specific value of horizontal load and overturning moment. Regarding stress behavior of soil supporting the bucket, due to soil densification and bucket movement, maximum stresses are seen near the bucket tip at the right inside of the bucket. The major part of the applied load is transferred by the bucket skirt. Numerical analysis modeling results show that the bucket rotation and displacement are highly dependent on the bucket geometry and soil properties in addition to loading conditions. Normalized equations and figures for the ultimate horizontal load and overturning-moment capacities are presented and can be used for the preliminary design of the bucket foundations in sandy soils.