Effect of Netted Collar on Maximum Local Scouring Depth of Cubic Bridge Pile Groups

Document Type : Research Article


Shahid Chamran University of Ahvaz, Faculty of Water Sciences Engineering, Ahvaz, Iran


Every year in various parts of the world a number of bridges are destroyed by flood just when we need them. Much of this destruction are due to scour around their piers. Erosion and the movement of the bed material due to the water flow say scouring. During this process, a hole is formed around piers that its depth to reach the depth of equilibrium, increases regularly. In this study a flume is used with 6 m length and width of 73 cm and bed slope near to the zero in the Hydraulic Laboratory of Shahid Chamran University of Ahvaz. In order to reduce the scour around the pile groups, a thin plate so-call “collar” was installed around the middle the pile group. The collars were simple and netted with opening of 30, 50 and 70 Percentage and were installed in three levels including: on the bed, 0.5D and 1D above the bed. The experiments were conducted under the conditions of clear water and three Froude Number equal to 0.12, 0.14 and 0.16 and the results were compared with the case of without collar mode. The results showed that simple collar installed on the bed and 70% netted collar placed at 0.5D level from the bed were reduced scour equal to 95% and 86%, respectively in compare with the non-collar.


Main Subjects

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