Experimental Investigation of Collar Performance with Rough Surface on Local Scour Reduction around Bridge Abutment with Rectangular Section

Researches show that one of the most effective factors on bridge destruction is bridge abutment scour. In this research, the role of collar as a control structure of bridge abutment scour was investigated along with the effect of its roughness. The results were then compared with smooth collars at the same condition. The results showed that the rough collars installed above the bed level showed a better performance in comparison to the smooth collars so that installation of the rough collar at a distance equal to 20 percent of the water depth above the initial bed level caused the performance of collar to be increased 14 percent, as compared to the condition with smooth collar. In the condition that the collars were installed above and below the bed surface, the performance of rough and smooth collars didn’t have a significant difference due to the small space under the collars.