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

This paper provides a practical stochastic method by which the maximum equilibrium scour depth around vertical piles exposed to long-crested (2D) and short-crested (3D) nonlinear random waves can be derived. The approach is based on assuming the waves to be a stationary narrow-band random process, adopting the Forristall wave crest height distribution (Forristall, 2000, "Wave Crest Distributions: Observations and Second-Order Theory," 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," J. Waterway, Port, Coastal, Ocean Eng., 114(5), pp. 599-641). An example calculation is provided. Tentative approaches to related random wave-induced scour cases are also suggested.