A comprehensive review of the research on local scour below subsea pipelines under steady currents and waves
Ming Zhao
Abstract
This paper presents a comprehensive review of studies of local scour below subsea pipelines. The review covers a variety of topics including onset of scour, scour depth, scour time scale, three-dimensional scour, pipeline sagging, multiple pipelines, scour protection, pipeline self-burial, scour-vibration interaction, scaling effects and cohesive sediment. Scour has been much more investigated by two-dimensional (2D) experimental and numerical studies than three-dimensional (3D). The fundamental mechanisms of 2D scour have been fully understood and many empirical formulae have been developed for predicting the scour depth under various conditions including current, waves, combined wave-current and vibrating pipelines. Some important research gaps are identified as a result of the review. 3D scour has not been sufficiently studied and more experimental data are required to support the methods that have been proposed or will be proposed. In addition, scaling effects, scour protection and self-burial have been reported but they are not sufficiently investigated. • Scour has been studied by more two-dimensional (2D) studies than three-dimensional (3D). • Scour mechanisms, scour depth and time scale of 2D scour have been full understood. • 3D scour has not been sufficiently studied and more data are required to support the proposed methods. • Scaling effects and self-burial have been reported but they need to be investigated further. • Recommendations for future studies are presented.