Scour countermeasures around cylindrical pier by using downscaled W weir

Scour is a significant concern for bridge design and maintenance, and scour countermeasures are often used to prevent or reduce erosion caused by scouring. The W weir is a grade control structure that serves many purposes, including scour controls at the bridge pier. A series of laboratory experimental runs were carried out by changing the size and height along with its location from the pier to the weir to optimize the structural configuration of downscaled W weir. It is observed from the experiments that the scour hole profile at the upstream of the downscaled W weir changes with the height of the weir. When the height of the weir was 1.0D (D = diameter of the pier), two small depressions of almost identical size were observed inside the main scour hole, one just in front of each upstream apex of the W weir. One cone-shaped scour hole was observed when the height of the W weir was 0.5D with its maximum depth in between the upstream apexes. The reduction of scour in front of the pier was more when the height of the weir was 1.0D. The maximum scour control achieved among all the different structural combinations of downscaled W weir was 47.66%. The maximum scour control was achieved when the downscaled W weir had a 2.0D size with the height of 1.0D placed at a 2.0D distance from the pier.