Experimental study of the effect of the length-to-width ratio and skewness angles of the pier installed at the bend on scour pattern

One of the causes of the destruction or damage of many bridges in the world is the local scour around the bridge piers. Accordingly, research on effective factors on the scouring pattern around the bridge piers is a necessity. In this study, the parameters of the scour hole created around rectangular piers, such as the depth, area and volume of the scour hole, and the effects of increasing the rectangular pier’s length-to-width ratio and its skewness angle towards the banks on scour hole parameters, bed topography changes and the downstream straight path in a 180° sharp bend has been investigated. The results showed that in a 180° sharp bend, the length of the rectangular pier should be at least 3 and at most 5 times its width. The pier with a length-to-width ratio of 3 had a better performance in terms of reducing scouring along the bend. The maximum depth of the scour hole around the piers occurs when the piers are located at 90°. Increasing the angle of attack caused by skewing the pier towards the inner and outer bank at 90° increases the depth and volume of the scour hole.