Scour below Pipeline in River Crossings

An experimental research on the scour produced under a pipe exposed to a stream is reported. Experiments were performed in a rectangular laboratory channel whose bed was composed of loose granular particles of two different diameters. Pipes of four different sizes were located either on top of the bed or at varying distances above it. The accelerations and higher water velocities generated by the presence of the pipe increased shear velocity, thus generating a scour hole. The results obtained showed that the Reynolds number of the pipe exerts a negligible influence on the scour process. By contrast, the Froude number was found to be an important parameter in the definition of the scour process. Good correlations between the Froude number of the flow and the most important characteristic dimensions of the scour hole were obtained, and different general relationships that allow the prediction of the characteristic dimensions of the scour hole are thus proposed.