Computational Fluid Dynamics Modelling of Pipe-Soil Interaction in Current

Subsea pipelines are subjected to wave and steady current loads which cause pipeline stability problems. Current knowledge and understanding on the pipeline on-bottom stability is based on the research programmes from the 1980's such as the Pipeline Stability Design Project (PIPESTAB) and American Gas Association (AGA) in Joint Industry Project. These projects have mainly provided information regarding hydrodynamic loads on pipeline and soil resistance in isolation. In reality, the pipeline stability problem is much more complex involving the cyclic hydrodynamics loadings, pipeline response, soil resistance, embedding and pipe-soil-fluid interaction. In this work Computational Fluid Dynamics (CFD) modelling is used to determine the submerged weight necessary for pipeline lateral stability, and the effect of soil embedment and soil porosity on pipeline lateral stability. The results show that increase in pipeline submerged weight, soil embedment and soil porosity increases pipeline lateral stability. The use of CFD provided a better understanding of the complex physical processes of pipe-soil-fluid interaction, and also reduces the need for expensive test facilities and complex design complications.