Examination of the local scour around the rectangular pipelines crossing meandering streams

ABSTRACTPipelines that are used to convey water, petroleum gas or any other fluid across a river aregenerally buried under the bed. The pipes may become partially exposed to action of a currentwhen a flood causes a general scour in the bed of the river. Prediction of the scour producedbelow pipelines placed transversally to a current on a movable bed constitutes an importantproblem in pipeline engineering practice.In this study, the scour depths around pipe, which have the square shape are experimentallyinvestigated. The results of dimensionless analysis obtained showed that the relativeequilibrium scour depth S/D are dependent on the relative flow depth (yn/D), Reynoldsnumber of the pipe (Re) and Froude number of the flow (Fr).The first chapter discusses the description of scour and its properties. The factors affected thescour has also explained.In the second section , boundary layer and water surface profiles are taken up.In the third section, the sediment transport mechanism and handicaps which effects the scourunder the pipelines were also explained.In the fourth chapter, some studies and numerical modellings about scour around pipelines arementioned.In the fifth chapter, experimental studies about the topic are mentioned.In the sixth and seventh sections , experiment results and regrection analysis are evaluated.Experiments were performed in a rectangular laboratory channel. Pipes of three different sizeswere located on the top of the bed. Froude number of flow was found to be an importantparameter in the definition of the scour process. Good correlations were achieved therelationship between Froude number of flow and dimensions of scour hole as the mostimportant parameters.Keywords: Submarine pipelines, local scours, river crossings, prediction of maximum scourdepth.