A study on the behaviour of offshore suction bucket foundations under cyclic axial compressive loading

Abstract

ABSTRACT Suction bucket foundations of offshore wind turbines (OWTs) are subjected to cyclic loads induced by wind and waves. The behaviour of buckets embedded in saturated sandy soil subjected to cyclic axial compression was studied using a finite element (FE) model. Accumulation of permanent soil deformations and excess pore water pressure in saturated sandy soil due to cyclic axial compression were taken into account by a fully coupled two-phase model combined with a hypoplastic constitutive model with intergranular strain. The Kozeny–Carman relationship was adopted for porosity–permeability dependence. The main focus was dedicated to the changes in load transfer via components of bucket with increasing number of load cycles. Loads that led to progressive failure, attenuation and shakedown behaviour were described. Effects of soil permeability and density, load frequency and amplitude, the bucket aspect ratio on the load transfer and bearing mechanism of the bucket were presented.