Estimating drag forces on suspended and laid-on-seafloor pipelines caused by clay-rich submarine debris flow impact

Abstract

Estimating the impact drag forces exerted by a submarine debris flow on a pipeline is a challenge. The conventional geotechnical based methods available to estimate drag forces on buried pipelines in unstable slopes are not applicable to a debris flow impact situation as they ignore or significantly underestimate the shear rate effects in the soil-structure interaction. The results of recent investigations indicate that a fluid dynamics approach in conjunction with rheological principles of non-Newtonian fluids provides a more appropriate way in the study of soil-pipe interaction for submarine debris flow impact situations. To that extent, this paper summarizes the results of a recent investigation on the impact of clay-rich submarine debris flows on suspended (free-span) and laid-on-seafloor pipelines. It presents a method to estimate the drag forces, longitudinal and normal to the pipe axis, for various angles of impact. The investigation comprised experimental flume tests and Computational Fluid Dynamics (CFD) numerical analyses. © Springer Science + Business Media B.V. 2010.