Experimental Study on Effect of Downstream Bed Sill on Local Scour Around Bridge Piers in Cohesive Sediment

Bridge pier scour is one of the three main causes of bridge failure. With the prospect of more severe and more frequent floods due to climate change, reducing the risk of bridge failure is becoming increasingly important. Therefore, different methods have been proposed to control scouring around bridge piers. In this study, the effect of bed sill on local scour around bridge piers that are embedded in cohesive soils has been studied experimentally. The bed sill was located in downstream and different distances from the piers. Cylindrical pipes with diameters of 60 mm and 75 mm were used as piers model.Result show that the effects of bed sill distance from piers in reduction of scour depth and scour volume is larger than the other parameter. By reducing the bed sill distance to the piers, scour depth and volume reduced. The best place to install bed sill is right next to the piers. It was found that the scour depth has no direct relationship with the piers Froude number.