Behavior of a Laterally Loaded Rigid Finned Pile Located on a Sloping Ground Surface

Abstract

Offshore wind turbines (OWTs) are used as renewable energy sources to generate electricity. Offshore, wind, and wave loads act as transverse loads on these turbines. Furthermore, the topography of the ocean is not always flat, varying from steeper to more gentle slopes. The passive resistance offered by the soil is reduced owing to the presence of the slopes. A finned pile is a unique rigid hollow steel tube with fins on both sides of the monopile used as the foundation for OWTs, increasing lateral resistance, ease of operation, and cost savings. A comparative study was undertaken based on experimental and numerical investigations on both monopile and finned piles placed at different infinite slopes (Flat, 1V:5H, 1V:3H, 1V:2H, and 1V:1H), pile positions (c = 0, 2.5, 5, and 7.5 Dp), and ground conditions. Three different densities of the soil (35%, 55%, and 75%) were analyzed to show how the behavior of the pile–soil stiffness affects the lateral load capacity. A numerical investigation was undertaken using PLAXIS 3D (version 1.6) finite-element software. The fin lengths and widths were varied to obtain the optimum fin size. An e/Dp (eccentricity to diameter) ratio of 12 was maintained for the experiment and numerical analysis. The displacement and rotation results of the monopile and finned pile were compared. The result shows an increase in lateral load capacity by 15%–40% when the monopile was replaced with a finned pile considering different ground conditions. In addition, the distance from the crest where the slope effect is minimum was found to be 7.5 Dp.