Scour Around Vertical Pile Foundations for Offshore Wind Turbines Due to Long Crested and Short Crested Nonlinear Random Waves

Abstract

This paper provides a practical stochastic method by which the maximum equilibrium scour depth around vertical piles exposed to longcrested (2D) and shortcrested (3D) nonlinear random waves can be derived. The approach is based on assuming the waves to be a stationary narrowband random process, adopting the Forristall wave crest height distribution (Forristall, 2000, “Wave Crest Distributions: Observations and SecondOrder Theory,â€‌ J. Phys. Oceanogr., 30, pp. 1931–1943) representing both 2D and 3D nonlinear random waves, and using the regular wave formulas for scour depth by Sumer et al. (1992, “Scour Around Vertical Pile in Waves,â€‌ J. Waterway, Port, Coastal, Ocean Eng., 114(5), pp. 599–641). An example calculation is provided. Tentative approaches to related random waveinduced scour cases are also suggested.