The effect of pipe spacing on marine pipeline scour

Abstract

Scour is a major threat to deep water pipelines. A study was performed to determine the relationship between pipe geometry and scour depth, and examine scour hole dimensions under multiple pipes. Model tests were conducted in a two-dimensional wave-current flume facility in which pipes were exposed to unidirectional flow and unidirectional flow with oscillatory motion. The model testing investigated pipes in contact with a sand bed and the effect of pipe spacing on scour. Scour hole profiles were measured and plotted to show the scour hole shape under multiple pipe systems. For two pipe systems, spacing between pipes of 1/2 pipe diameter resulted in less scour depth than full diameter spacing. Unidirectional flow with oscillatory motion resulted in less scour than unidirectional flow. Keywords: Marine engineering; Ocean currents; Stress mechanics; Underwater structures. (KT)