Advanced characterization techniques of the scour hole around a bridge pier model

Abstract

Local scouring around bridge foundations is a major reason for bridge collapse worldwide. It occurs due to the formation of vortices around bridge foundations as a result of changing the unidirectional approach flow into the three-dimensional field in an erodible channel bed, leading to the development of a scour hole in its vicinity. In the present work, two different techniques were applied for a full characterization of the scour hole geometry developed in a sand bed flume experiment by means of a Kinect sensor and a close-range photogrammetry. These advanced survey and sensor technologies offer efficient techniques of deriving point clouds and Digital Elevation Models (DEMs), respectively. The potential, limitations and results of both techniques are herein examined and conveniently compared, including a description of measurement devices, reference points and respective software. Reliable and accurate estimates of the topographic representation of the scour hole and inherent features were obtained. The design of the bridge pier used, with a 0.14 m wide rectangular round-nose concrete column (henceforth termed as oblong pier), replicates the typical shape used in the 19th and 20th centuries, and are the most common in Portugal.