INVESTIGATING SCOUR DEPTH AROUND BRIDGE PIERS IN CURVED CHANNELS

Local scour around bridge piers is one of the most common causes of bridge failures . Many researchers studied the scour around the piers of bridges in straight channels. However, there is little information about the scour at bridge pier in a curved channel. In this paper, scouring is studied in curved channel at 30 degrees. Various piers forms were investigated to study local scour in the middle of the channel. The experimental study was conducted in a glass-walled8 m long rectangular flume (i.e. 30 cm x 60 cm). It encompasses three parts (i.e. the first and last part are 3 m long, 60 cm wide and 30 cm high, the third part, at its middle, is curved with angle 30 degrees on the horizontal, 2 m length. The experimental program was designed to test relative distance (b / B = 0.5) under 5 discharges (i.e. 13.89, 19.41, 23.77, 28.04 and 30.64 l/sec). An ultrasonic device was used to measure the water levels and depths as well as the scour length so as the depth. This is achieved to investigate the pier type and shape efficiency in reducing the scour depth. It was found that the best performance was achieved in the case, where the substrate was placed in the middle of the waterway and the inclination angle was equal to zero, where the hexagonal reduced the scour depth by 34%,relative to the maximum depth of scour.