Scour Below Pipelines and Around Single Vertical Piles for Bichromatic and Bidirectional Waves

Abstract

This article provides a method by which the scour depth and scour width below pipelines, and the scour depth around single vertical piles as well as the time scales of scour for both structures due to bichromatic and bidirectional waves are calculated. The scour and time scale formulae summarized by Sumer and Fredsøe (2002) as well as the bottom shear stress formulae under bichromatic and bidirectional waves by Myrhaug et al. (2023) are used. Results for unidirectional bichromatic waves and symmetrically bidirectional monochromatic waves are provided, showing qualitative agreement with what is expected physically. Qualitative comparisons are made with the data from Schendel et al.’s (2020) small scale laboratory tests on scour around a monopile induced by directionally spread waves. Applications to related cases for pipelines are also suggested. In order to conclude regarding the validity of the method for pipelines and vertical piles, it is required to compare with data in its validity range.

Keywords

Scour depth and width / Time scales / Seabed pipeline / Vertical pile / Shear stress / Bichromatic and bidirectional waves / Qualitative comparison with data

RIGHTS & PERMISSIONS

Harbin Engineering University and Springer-Verlag GmbH Germany, part of Springer Nature