Failure Envelopes of Bucket Foundations for Offshore Wind Turbines under Combined Loading Including Torsion

The loading condition of bucket foundations for offshore wind turbines is very complicated and often under combined loading, but the torsion is always ignored. So, it is necessary to investigate the failure envelopes including torsion of bucket foundations. Under the premise of validating the reliability of the numerical model by comparing with other published data, failure envelopes in each loading space are obtained and the applicability of swipe test for the determination of H-T failure envelope and M-T failure envelope of bucket foundations is explored. The impacts of torsion and aspect ratio on the combined bearing capacities are studied. While revealing the law of impacts, equations are proposed to determine the respective failure envelopes and evaluate the combined bearing capacities. The V-H-M-T failure envelope can reveal the torsion effect on envelope under traditional V-H-M loading, the results show that the normalized V-H-M failure envelopes under different torsions almost coincide, torsion effect can be easily considered according to this characteristic.