Experimental Investigation of the Effect of Diameter and Placement Level of Lattice Collars on Scour Reduction around Bridge Pier

In this research, the effect of lattice collar on reducing scour around the bridge pier was experimentally studied. A series of experiments were conducted in a flume with length of 6m and width of 0.6m. For evaluation of scouring phenomenon a cylindrical pier 60 mm in diameter, four different sizes for collars and three various levels for collars placement were used in clear-water conditions. The results revealed that the minimum scour depth occurred with lattice collars with width of 2.5 and 3 times of the pier diameter (2.5Dp and 3Dp) that has been installed at the 0.1Dp level under the bed, where the maximum scour depth decreased by 73%. Whereas scour depth decreased by 40% due to installation of lattice collars with width of 1.5Dp and 2Dp at the 0.5Dp level under the bed. Also, the result showed that the efficiency of lattice collars was about 20% more than non-lattice. Generally the scour volume around bridge pier at the 0.1 Dp, 0.5 Dp and Dp levelunder the bed decreased by 58%, 60% and 10%, respectively due to lattice collars installation.