Three-Dimensional Characterization of Laboratory Scour Holes Around Bridge Piers

The presence of a bridge foundation leads to the formation of a scour hole, from which entrainment and transport of sediments are controlled by the turbulent structures therein developed. Hence, once formed, these scour holes interfere significantly with the scouring process in several ways, for instance, by modifying the incoming flow patterns. Therefore, a three-dimensional survey of the scour hole and the characterization of the deposition features is essential for prevention and safety control purposes. To investigate this, scouring experiments around two oblong bridge piers were performed in a tilting flume of the Portuguese National Laboratory of Civil Engineering (LNEC), under live bed flow conditions. A comprehensive characterization of laboratory scour holes was performed using two advanced image-based measuring techniques, namely close-range photogrammetry and the Kinect V2 sensor. The produced 3D bed morphology models provided detailed measurements, with significant accuracy, with quite similar results between the characterization approaches. A database for calibration and validation of numerical models is thus provided.