» Research Note «Separated and Combined Effects of Sacrificial Piles, Collar and Slot on Reduction of the Local Scour around the Bridge Piers

There are different techniques to control and reduce local scour around the bridge piers. In this study the effects of collar shape, size and depth of placement on the pier were investigated. The effects of sacrificial piles, slot and collar separately and combinations of double and triad of them on the scour depth were studied. The result showed that the square collar was more effective than circular and lozenge collar in decreasing the scour depth. The installation of collar below the bed level, especially in the depth of -0.1 D was more effective than -0.4D and on the bed level in decreasing the scour depth. The maximum reduction of the scour depth occurred for square collar which equaled to 70% and the next was sacrificial piles with 46.67% and then the slot with 31% had the highest effect, respectively. Combination of sacrificial piles and square collar on the pier with 75% reduction was most effective in decreasing the scour depth.