Evaluation of Diameter and Distance of Sacrificial Piles from the Bridge Pier in Reducing Local Scour

Abstract

In this research, it was analyzed influence of variation of sacrificial piles diameter, as well as the distance between front pile and the face of the pier in reducing local scour depth. For this purpose, it was calibrated a physical test of an isolated cylindrical pier developed in a previous research. For calibration, numerical models were made with Manning's roughness coefficients of the sand of 0.023, 0.024 and 0.025 and the application of Froechlich and Colorado State University (CSU) equations to calculate the local scour depth. After that, 12 numerical models were made with the addition of sacrificial piles in a 30° triangular configuration to the calibrated model. The diameters of sacrificial piles were 5, 6, 7.5 and 10 mm and distances between front pile and the face pier were 75, 90 and 105 mm. According to the results, the highest percentage of local scour reduction was obtained when the sacrificial piles had a diameter of 10 mm and the distance between the front pile and the pier was equal to 105 mm. In this sense, when the distance between the front pile and the face pier was greater, the percentage of local scour reduction was higher. Also, based on the results, it is concluded that, Froechlich's equations and CSU lose precision when there are sacrificial piles.