Numerical Studies on the Working Mechanism and Bearing Capacity of Bucket Foundations for Offshore Wind Turbines

Bucket foundations represent a new type of foundation for offshore wind turbines. They are large cylindrical structures that open at the base and close at the top. Compared with traditional offshore pile foundations, bucket foundations exhibit the advantages of shorter installation periods, lower material costs, and more rational bearing patterns. The complex interaction between a bucket foundation and soil defines the loading mechanism of this foundation type, and its failure mode has yet to be clearly defined. A simplified limit equilibrium method or other oil-platform design codes (e.g., API) is typically adopted to design bucket foundations. However, the simplified limit equilibrium method does not reflect the working characteristics of the soil in the foundation, thus resulting in a relatively considerable deviation. A numerical analysis is performed to simulate the working mechanism and evaluate the bearing capacity behavior of bucket foundations. Calculation results show that the bearing characteristics of bucket foundations are different from those of the simplified limit equilibrium method, and that failure occurs and develops in the soil within the bucket wall. This difference causes the simplified limit equilibrium method to overestimate the bearing capacity of bucket foundations.