Research on bearing behavior of secant piled bucket foundation for onshore wind turbines

Abstract

In this paper, a new type of secant piled bucket foundation (SPBF), which consists of secant piles to form a bucket-shaped foundation is creatively proposed for onshore wind turbines. Before the implementation of the world's first experimental prototype, it is necessary to study the safety and bearing characteristics of the new foundation under horizontal-moment load to provide technical support for the implementation of the prototype. Therefore, model test and finite element (FE) analysis based on software ABAQUS were carried out. First, with the model test, the FE menthod is verified, and the failure mode of model SPBF under H-M load in saturated sand has been determined to be rotation with a small amount of horizontal slip. In addition, the feasibility of the SPBF is demonstrated by FE method. Then, the influence of geometric effect of bucket skirt on the SPBF are investigated in terms of bearing capacity, structural stress and deformation, the results show that the bearing behavior is influenced by the pile length and the failed secant face, but is less affected by the pile number of bucket skirt. Finally, the first test prototype SPBF designed for a 3.3 MW onshore wind turbine is introduced, and the SPBF can approximately save the land occupation by 40 %, steel bars consumption by 22 %, and concrete consumption by 9 % compared with the traditional pile foundation.