Evaluation of horizontal submarine slide impact force on pipeline via a modified hybrid geotechnical – fluid dynamics framework

There are situations in offshore energy development where potential impact forces between submarine slides and pipelines need to be estimated. The horizontal slide – pipeline impact force, parallel to the main travel direction of the sliding mass and normal to the pipeline axis, is generally dominant compared with other force components and hence of particular concern. In practice, pipelines may be suspended at varying distances above the seabed (gap) and existing methods do not consider how this will affect the horizontal slide – pipeline forces. This paper investigates the effects of pipeline–seabed gap and pipeline diameter on the horizontal slide – pipeline impact force via 181 computational fluid dynamics (CFD) simulations at Reynolds numbers of 0.36–287. Results show that variation in the pipeline–seabed gap and pipeline diameter alters the slide mass flow behaviour as it flows past the pipeline and hence the impact force when the pipeline–seabed gap is below a critical value. A modified hybrid geotechnical – fluid dynamics framework for estimating the horizontal impact force is proposed by considering the effects of the pipeline–seabed gap and pipeline diameter, which is validated with existing experimental datasets.