Experimental study of the effect of submergence ratio of double submerged vanes on topography alterations and temporal evaluation of the maximum scour in a 180-degree bend with a bridge pier group

摘要

ABSTRACT Various protective methods are incorporated in order to change the flow pattern and reduce the intensity of the vortices around the piers with the aim of reducing scour at bridge piers. One of these methods is the employment of submerged vanes at the upstream side of the bridge piers. This study investigated the effect of the submergence ratio of the submerged vanes in scour reduction around a single pier and a group of piers. The results indicated that the greatest reduction in the maximum scour depth, the scour hole volume, the maximum sedimentary bar, and the scour hole area around the piers occurred in experiments with a single pier and triad piers with a longitudinal direction in combination with 75%-submerged vanes. At this submergence ratio, the maximum scour depth and the scour hole volume decreased by nearly 30 and 59% respectively in the single pier test including the submerged vanes, and by nearly 23 and 37% respectively in the triad pier group test with a longitudinal direction including the submerged vanes in comparison to the test with no submerged vane installed.