Effect of Pier Inclination Angle on Local Scour Depth Around Bridge Pier Groups

The primary objective of this study is to investigate experimentally local scours around bridge pier groups at various inclination angles of piers and also to develop empirical local scour depth equations. In the study, two bridge pier groups are used. In each pier group, the most upstream and downstream piers are placed in an inclined manner at \(10^{\circ }\) and \(15^{\circ }\). The vertical case was also employed for comparison purposes. Seventy-two experiments each lasting 6 h are conducted under uniform-flow and clear-water conditions for a range of water depths and velocities on the uniform bed material. This study confirms that inclination of cylindrical piers located at the most upstream and downstream locations of pier groups directly affects the local scour in a favourable manner, with a substantial reduction in the local scour, especially around the most upstream pier. Moreover, the flow intensity and relative flow depth are important factors that characterize the local scour. An empirical scour depth equation is developed for each pier inclination angle for design engineers. Comparisons with previous studies are made and results discussed.