Evaluation Method for Composite Bearing Performance of Pile Anchor Foundations in Layered Soil
This study addresses the bearing failure mechanisms of pile anchor foundations for floating offshore wind turbines in layered soil. Using finite element analysis, the research investigates the coupled bearing performance under V-H, V-M, and H-M load combinations in complex layered soil conditions, based on the engineering geological conditions of an offshore clean energy site. A failure envelope method is employed to systematically evaluate the foundation's capacity. The study establishes a calculation method for assessing the in-place bearing capacity of pile anchors using limit load envelopes. Key findings indicate that the V-H load space envelope can determine the bearing performance dominated by uplift and lateral sliding failure. The eccentricity of the mooring point induces bending moments that significantly reduce the uplift bearing capacity, with the reduction increasing as the moment increases. The research provides a practical method for evaluating pile anchor bearing capacity under combined loads, facilitating the application of pile anchors in offshore clean energy development. The finite element model uses Plaxis 3D, with a pile diameter of 5.5 m, length of 77.5 m, and wall thickness of 100 mm, and employs the NGI-ADP model for clay. The study fills a gap in understanding pile behavior in layered soils, offering a robust tool for engineering design.