Influence of scour hole geometry on lateral bearing capacity of nearshore rigid piles

Rigid piles supporting nearshore wind turbines in marine environments are subjected to lateral loads and local scour, which reduces their bearing capacity. This study investigates the influence of scour hole geometry on the lateral bearing capacity of rigid piles utilizing the finite element limit analysis method (FELAM) for efficient prediction. The accuracy of the numerical model is validated against existing studies. Extensive analyses are then conducted, varying scour hole geometry, shear strength parameters, and pile slenderness ratio. Dimensionless lateral bearing capacities and reduction factors are presented in design charts for practical engineering use. Key findings reveal scour depth as the dominant factor affecting capacity, with a critical scour width (3 ∼ 5 times pile diameter) beyond which further increases have a negligible impact. Scour angle positively correlates with capacity, but its influence diminishes beyond a certain scour depth threshold (3 times pile diameter). The internal friction angle exhibits complex behavior, with its influence reduced as scour depth increases. Higher slenderness ratios enhance lateral bearing capacity under scour. The derived reduction factors can be reasonably extended to cases with varying cohesion and slenderness ratio, providing a robust tool for design applications.