Author(s): S. Yurdagul Kayaturk; M. Ali Kokpinar; Mustafa Gogus
Linked Author(s): Mehmet Ali Kökpinar
Keywords: Bridge pier; Scouring; Collar; Scour reduction; Sacrificial pile
Abstract: Various methods have been attempted to control scouring around bridge foundations, such as using riprap, slots through the bridge structures, a group of small piles in front of the bridge structures, and collars. In this study the effectiveness of collars placed on bridge piers and also sacrificial piles placed upstream of the bridge piers on the local scour around the bridge piers were tested. Experiments were carried out near the threshold of sediment motion with two circular piers having diameters of D=5 cm and 10 cm. The sizes of collars placed around the bridge piers were Dc=3D and 5D for the pier of D=10 cm, and Dc=2D and 3D for the pier of D=10 cm. Collars were placed around the piers at three different levels as; Zc= 0. 00 cm, -2. 50 cm, and -5. 00 cm where Zc is measured with reference to the bed level. After each experiment, collar effectiveness on the maximum scour depth and on the time development of the maximum scour depth around the pier were investigated. It was found that, wider collars could protect the piers against erosion more effectively. The maximum scour reduction was obtained as 73% with Dc=5D when the collar was placed at the bed level. The results of the experiments related to the time development of the scour hole showed that the use of collars around the piers was very effective in slowing down the development of scouring. The sizes of the sacrificial piles placed upstream of the bridge piers were d=0. 5 cm, 1 cm, 1. 5 cm and 2 cm for D=5 cm, and d=1 cm, 2 cm, 3 cm and 4 cm for D=10 cm. All sacrificial piles were placed at a distance of L=2D from the center of the bridge pier to the center of the sacrificial pier. It was observed that when the sacrificial pile having the ratio of d/D=0. 4 and placed at a distance of 2D, it could reduce the maximum scour depth around the pier about 35% compared to the unprotected pier.
Year: 2005