Numerical study on the combined bearing performance of tripod-bucket foundation for floating and fixed wind turbines

Abstract

The tripod-bucket foundation has been proposed as an alternative foundation type for floating and fixed wind turbines. Its combined bearing capacities are necessary for describing the ultimate load combinations of the foundation. In this paper, three-dimensional finite element models of tripod-bucket foundations are constructed based on the structure-soil-interaction. Considering the foundation being used for floating and fixed wind turbines, the vertical upward and downward load conditions are involved and the calculation results were compared in detail. The uniaxial ultimate bearing capacities V_ult, H_ult, and M_ult, as well as the V-H, V-M, H-M, and V-H-M failure envelopes of the tripod-bucket foundation in homogeneous clay are calculated. The failure mechanisms of soil surrounding the tripod-bucket foundation under different uniaxial loads are compared. Results show that the bearing capacities are much lower when the tripod-bucket foundation is subjected to upward loads than the downward load. The modes of the H-M envelope changing with the vertical load are quite different, comparing the vertical upward and downward load conditions.