Method of Determining the Failure Envelopes Including Torsion of Bucket Foundations for Offshore Wind Turbines

Abstract

The bucket foundations for offshore wind turbines are often under combined loading, but the role of the torsional load T is often not considered. As a result, the optimal method for determining the failure envelopes including torsion of bucket foundations has not been identified. Bucket foundations with different embedment to diameter ratios (L/D) are studied to investigate the applicability of swipe test and combined load-displacement searching method for the H-T and M-T failure envelopes. Study shows that the swipe test is only applicable for determining the H-T failure envelope of bucket foundation when L/D is less than 0.25.Under the remaining conditions, the optimal method is the combined load-displacement searching method. The effect of torsion on the horizontal and moment bearing capacities is revealed through the H-T and M-T failure envelopes.