Lateral-Moment Loading Capacity and Bearing Behavior of Suction Bucket Foundations for Offshore Wind Turbines in Sand

Suction bucket foundations are promising foundation options for offshore wind turbines, which are usually subjected to a relative high lateral-moment loading. To investigate the lateral-moment loading capacity of bucket foundations, a group of three-dimensional finite-element simulations with different bucket dimensions in both loose and dense saturated sand was carried out based on centrifuge tests. The numerical methods were validated by comparisons with the results of centrifuge tests and assessed by sensitivity analyses regarding the influences of soil properties and soil-foundation interface parameters. The interaction between the bucket and surrounding soil was illustrated in order to investigate the bearing behavior and failure mechanism of the bucket foundation. It was shown that in the ultimate state, the maximum passive earth pressure acting on the external skirt in the loading direction is approximately four times larger than that on the internal skirt. Furthermore, parametric studies on the L:D ratios (L is the skirt length and D is the bucket diameter) and loading eccentricity were conducted and discussed. Consequently, a modified calculation method was proposed to predict the ultimate lateral-moment loading capacity of bucket foundations and the method was validated by field and laboratory data.