Experimental Investigation of Scour and Pressures on a Single Span Arch Bridge Under Inundation

This paper presents two experiments, carried out in a 605mm-wide flume, to investigate scour and hydrodynamic pressure on a scaled model of a single span arch bridge. The geometry of the bridge model is scaled down according to a prototype bridge, with hydraulic conditions of the experiments representing a small river. Measured scour depths showed that flow vertical contraction by the arch bridge is higher than that of flat-deck bridges. Effect of a single cylindrical debris on scour was also evaluated and found to be negligible at the considered flow depth. Temporal variation of hydrodynamic pressure with scour evolution was also measured. It was found that temporal evolution of scour can reduce hydrodynamic pressure significantly at the initial base of the abutment at downstream face of the bridge, which can erode mortar from the masonry composition of an arch bridge