Bearing Performance of Single-Column Composite Bucket Foundations for Offshore Wind Turbines Under Scour Evolution

• • Scour depth increase from 2 m to 10 m reduces lateral stiffness by 15% and natural frequency by 7–8%, directly impacting serviceability and fatigue life of offshore wind turbines. • • Complete scour reduces ultimate bearing capacity by only ~10%, confirming that the foundation's load-bearing mechanism is dominated by internal soil plug and base support rather than external skirt friction. • • Cyclic loading under scoured conditions significantly decreases horizontal stiffness and increases cumulative rotation, with effects far more pronounced than static loading, necessitating fatigue-based design checks. • • Rock dumping protection is predicted to restore horizontal stiffness to >90% and ultimate bearing capacity to >95% of unscoured state, offering a quantifiable retrofitting strategy for existing installations.