Research on Liquefaction Resistance of Bucket Foundation for Offshore Wind Turbines

Abstract

[Introduction] With the increasing demand for clean energy, the offshore wind power sector has seen a spurt of progress in recent years, and the bucket foundation has become the preferred choice for offshore wind turbines considering its good economy, convenient construction, and recyclability. Due to the widespread distribution of seismic zones in China, the seismic performance of bucket foundation is a crucial consideration for structural design. The bucket foundation is featured by high structure stiffness, so that the probability of structure damage caused by earthquake is low, and the failure under earthquake is mainly caused by the liquefaction of the foundation soil. For this purpose, the paper focuses on the seismic performance of bucket foundation in sandy soil. [Method] The liquefaction resistance of sandy soil for bucket foundation was analyzed by shaking table tests in this paper. The study objects included four types of bucket foundation in sandy soil, namely mono-bucket foundation (MBF), composite bucket foundation (CBF), three-bucket jacket foundation (TBJF) and four-bucket jacket foundation (FBJF). [Result] By carrying out shaking table tests, the excess pore pressure ratios of sandy soil for different types of bucket foundation under earthquake are obtained, and the impact mechanism of bucket foundation on the anti-liquefaction performance of sand soil is clarified. [Conclusion] The bucket foundation can improve the liquefaction resistance of sand, since the additional load effect of the superstructure and the hoop effect of bucket skirt weakens its shear shrinkage. The test results of MBF are compared with those of CBF, and the test results of TBJF are compared with those of FBJF. It is found that the seismic performance of CBF and FBJF is respectively superior to that of MBF and TBJF.

Keywords

• bucket foundation
• liquefaction
• shaking table test
• pore pressure
• seismic response