Effects of Collars on Scour Reduction at Bridge Abutments

Abstract

Bridge failures are generally resulted from scour of the bed material around bridge piers and abutments during floods. In this study, scour phenomenon around bridge abutments and collars, located at abutments as scour countermeasures, were experimentally investigated. Based on the results of 97 experiments conducted, the effect of various sizes of collars which were located around the abutments at different elevations, on the scour reduction at bridge abutments was determined. The results were compared with previous studies, and the effect of the sediment grain size on the performance of abutment collars was emphasized. It was noticed that when the collar width was increased and it was placed at or below the bed level, the reduction in the maximum local scour depth increases considerably. It was also seen that the change of the sediment size did not affect the optimum location of the collar at the abutment, which yields the maximum scour reduction around the abutment.