Modelling of laterally loaded screw piles with large helical plates in sand

Screw piles, where flanges or plates are typically located close to the pile tip, are used in onshore applications such as transmission tower foundations. This is due to their high axial capacity, ease of installation and low material use. In offshore applications, such as jacket structure foundations for deep water renewables, they would be subjected to significant lateral loads which may not suit their low bending strength, associated with the low cross-sectional area of typical screw pile cores. To overcome these limitations, screw piles may be provided with additional flanges located close to the mudline where the lateral deformations of the bending pile are highest and where they may therefore be more effective in resisting lateral loads. This paper presents results of 3D Finite Element Analysis (FEA) investigating the lateral performance of such piles as a function of flange diameter, and suggests guidance for the optimum axial position of near surface flanges. Results suggest that near surface flanges make a moderate contribution to lateral capacity but increasing pile cross-section is more efficient.