EFFECTS OF SHAPE AND SKEW-ANGLE OF BRIDGE PIERS ON LOCAL SCOUR

In this study, laboratory experiments were performed to evaluate the effects of shape and skewness-angle of bridge piers on the local scour. Experiments were carried out in the laboratory using a transparent rectangular flume with a steel frame structure flume. The experimental work has been carried out under clear water conditions using three sets of piers (4 cm in width and 40 cm in length) arranged in one row with two different shapes (lenticular and oblong) and four different skewness-angles (alpha) (0 degrees, 15 degrees, 30 degrees, 45 degrees), while the ratio of the spacing between piers to the width pier was kept constant at 2. Additionally, the effects of flow velocity on the local scour were examined at three velocities, namely 0.17, 0.23, and 0.27 m/s. The flume bed was made from sand with average grain size (d50) of 0.71 mm, and a geometric standard deviation of 1.14. The obtained results showed that the depth of the local scour was significantly affected by all the studied parameters (skewness-angle, flow velocity, and shape of piers). The maximum scour depth (13.2 cm) was noticed in the lenticular piers when the skewness-angle and flow velocity were 30 degrees and 0.27 m/s, while the lowest scour depth (1 cm) was noticed in the lenticular pier when the skewness-angle and flow velocity were 0 degrees and 0.17 m/s, respectively.