This study explores the performance of finned monopiles as an innovative foundation solution for Offshore Wind Turbines subjected to cyclic loading under varying seabed conditions. Traditional monopiles face challenges related to stability when installed on sloped terrains, which are common in offshore environments. To address this, the research investigates the effectiveness of rectangular fins attached along the monopile's length to improve lateral resistance and reduce accumulated rotation. Experimental and numerical analyses were conducted across different slope gradients (flat, 1V:5H, 1V:3H, 1V:2H), pile positions (0Dp, 2.5Dp, 5Dp, 7.5Dp), and soil densities (35%, 55%, 75%), applying cyclic loading at 0.25 Hz over 1000 cycles with lateral load amplitudes (xi b) of 30%, 40%, and 50%. This study is the first to investigate finned monopiles under cyclic loading on sloping seabed conditions, demonstrating a 30-60% improvement in lateral resistance by increasing the passive soil resistance by reducing the rotation compared to monopiles. This work addresses the challenges of Offshore Wind Turbine foundations in complex topographies. Numerical modeling using PLAXIS 3D closely aligned with experimental findings, confirming the effectiveness of finned monopiles in enhancing stability on sloped seabeds. These findings suggest that finned piles offer a robust foundation alternative for Offshore Wind Turbines, particularly in challenging environments with variable seabed topography.

In order to study the failure mechanism of a finned pile foundation under horizontal cyclic loads, a physical model test of the pile-soil interaction of finned pile is designed in this paper. Based on the model tests, the pile top displacement, the cyclic stiffness of the pile foundation, and the response of pore water pressure within the soil around the pile were fully studied for the finned pile foundation under horizontal cyclic loads. It is found that the cyclic stiffness attenuation of the finned pile foundation is more severe than that of a regular single pile foundation, but the final stiffness at equilibrium is still greater than that of a regular single pile foundation. The accumulation of horizontal displacement at the pile top and pore water pressure within the soil around the pile mainly occurs in the first 1000 loading cycles, and an increase in fin plate size will reduce the magnitude of pore water pressure and pile top displacement. This study can not only deepen the understanding of the failure mechanism of finned pile foundation under horizontal cyclic loads, but also provide guidance for the design of the finned pile foundation.