Soil response along the pile shaft of a shared anchor subjected to multi-directional lateral loading

Shared pile anchoring enables multiple floating wind turbines to be secured to a single foundation, offering significant potential to reduce mooring costs and environmental impact. However, this concept introduces complex multi-directional cyclic loading on anchor piles, which remains insufficiently understood and is not yet addressed in current design guidelines. Preliminary evidence suggests that such loading may adversely affect pile response. This paper presents a combined experimental and numerical study to improve the understanding of soil–pile interaction under multi-directional loading. A sun-type lateral loading pattern, consisting of monotonic load sequences applied at 30° increments, is analysed. This study (i) characterises the pile response under this loading scheme, (ii) validates a numerical model for further investigation of multi-directional cyclic loading, (iii) examines the evolution of the p–y curves, and (iv) demonstrates how combined physical and numerical modelling can highlight the three-dimensional effects on soil response, including void ratio changes. Overall, the work presents a combined approach to better understand soil behaviour around the pile shaft under complex loading paths, providing a basis for the development of more robust and reliable design methods for floating wind turbine shared anchors.