Experimental Investigation of Effect of Sill Location on Local Scour Around Inclined Bridge Piers Group

After construction of bridge pier in a river, a 3D complex flow pattern forms around piers and erosion of bed material occurs and if foundation depth or piles depth was not sufficient, the bridge will be collapsed. One of devices to reduction of scour around bridge piers is an installation of sill beside of piers. In this research, effect of sill on reduction of scour around the inclined bridges piers group under various hydraulic condition and top level of installation of foundation was investigated experimentally. The model of bridge pier was 1/190 scaled of 8th bridges of Ahvaz, Iran, which had inclined rectangular of 2.5 cm length and 3.5 cm width and was placed on the foundation of 10 cm width and 16 cm of length with inclination of 28 degree. Experiments was conducted for different location of sill (front, middle and downstream) of foundation which installed at relative level, height of top of foundation to width of it, -1, -0.5, 0 and 1. Comparison of results showed that installation of sill in front of foundation had the best performance to decrease of scour depth. Furthermore, the reduction of scour depth as the top level of foundation was placed at same level of bed, was considerable.