Effects of Bridge Pier Location and Debris Accumulation on Equilibrium Morphology

Scour at bridge piers is one of the most studied and challenging problems for hydraulic engineers. Many researchers analyzed such scour phenomenon, focusing on the effect of hydraulic conditions and geometric configurations. In particular, previous analyses focused on the scour evolution and equilibrium configuration under both clear- and live-bed conditions, providing useful design criteria, accounting for the effect of hydraulic conditions and pier geometry. On the contrary, only a few studies deal with the effect of debris accumulation on scour evolution and equilibrium configuration. But, to the best of authors’ knowledge, none of them analyzed the effect of debris accumulation for an isolated pier located at different transversal positions with respect to the channel bank. In order to fill this gap of knowledge, we conducted experimental tests by varying the transverse position of the pier within the channel. Furthermore, we tested different debris accumulations varying the percentage blockage ratio. Experimental results revealed that scour equilibrium configurations are affected by the tested parameters. Therefore, the aim of this paper is to present a preliminary analysis of the scour hole features, highlighting similitudes and differences in terms of scour characteristics caused by the pier location in the presence of debris accumulation.