Seismic responses of two bucket foundations for offshore wind turbines based on shaking table tests

Abstract

Sand liquefaction under seismic load causes severe failure of bucket foundations for offshore wind turbines. This study conducted shaking table tests for two different types of bucket foundations: mono bucket foundation (MBF) and composite bucket foundation (CBF). Furthermore, five groups of EI-Centro seismic waves with different intensities were applied. The excess pore water pressure and acceleration of the foundation soil were measured. The influences of bucket foundations on the seismic behavior of sand were explored by comparing the excess pore water pressure and acceleration at different positions. Moreover, the seismic responses of two types of bucket foundations were compared, and the effects of bulkheads in CBF on the seismic performance of foundation soil were clarified. The test results show that the seismic response of the soil inside the bucket is clearly suppressed compared with the soil outside the bucket, and thus the risk of liquefaction is lower. Furthermore, the seismic response of the CBF is significantly weaker than that of the MBF, and the anti-liquefaction performance of the CBF soil foundation is better. This implies that CBFs are safer than MBFs during earthquakes.