Evaluation of hydrodynamic forces on offshore wind power piles induced by submarine landslides at various impact depths

Abstract The rapid growth of offshore wind farm construction requires reliable pile foundation designs that can withstand complex marine loads. However, current design practices for these foundations often neglect the potential threat of submarine debris flows, which can exert highly destructive forces. This study employs a CFD approach to simulate the effects of submarine debris flows on piles in intricate marine environments, with model accuracy validated against a series of laboratory experiments calculating lateral forces from debris flows. We investigate the impact of debris flows on piles across a range of Reynolds numbers, including variations in rheological properties, density, impact velocity, and initial debris flow heights. Our results reveal that the dominant force exerted by submarine debris flows on piles is primarily a horizontal drag force. We identify three distinct stages in the impact process and emphasize the peak drag force as the critical load on the pile. The study provides a comprehensive analysis of the mechanisms driving variations in drag force and highlights the nonuniform distribution of drag forces along the pile’s length. The debris flow height significantly influences not only the magnitude of the peak drag force but also the action point location of this force along the pile. Finally, we propose quantifiable methods for evaluating the peak drag force coefficient and its action point, enhancing the design resilience of pile foundations against submarine debris flows.