Bearing characteristics of mono-column composite bucket foundation in sand for offshore wind turbines

Abstract

Using a new steel compartment structure, the mono-column composite bucket foundation applied in the South China Sea deep-water project for the first time is based on the optimization of the steel-concrete composite bucket and is suitable for wind farms with a water depth of more than 30m. However, at this stage, there are few studies on large-diameter mono-tube multi-compartment bucket foundations, especially those related to the bearing characteristics of mono-column composite bucket foundations after long-term service. In this study, a cyclic load test is carried out on a mono-column composite bucket foundation in sand, and the influence of cyclic load factors on the cumulative rotation angle, cyclic stiffness, and ultimate bearing capacity after cyclic loading of the foundation is analyzed, and the bearing characteristics of the foundation are analyzed by finite element analysis. The results show that after the cyclic loading, the bearing capacity and stiffness have a certain increase compared with before the cyclic loading in sand. The ultimate bearing capacity calculation formula based on the Mohr-Coulomb strength criterion derived from the limit state of the foundation failure has higher reliability compared with the test results and can be used to predict the bearing capacity of the mono-column composite bucket foundation.