Failure of bridges due to scour in the vicinity of piers poses a challenging problem to the hydraulic engineers. The main objectives of this study were to determine scour hole dimension, with its maximum scour depth as a function of time and at the equilibrium stage, the scour hole shapes and the investigation of the influence of sills on the scour hole at the same stage. Hence, using 3D simulation model (SSIIM) accompanied with experimental work have been used in this study. Four different flow discharges at the presence of bed sill as a physical barrier against scour were studied to compare with non-presenting bed sill condition. According to the results, bed sill can decrease either scour depth or dimensions of the scour hole. The model was calibrated and verified using the measured experimental data, and was used in test runs comparing performance under various flow discharge, flow depth, and bed sill conditions. Model performance was found acceptable, indicating its usefulness in the simulation of scour process around the circular bridge pier. As a consequence, it is possible to predict the location of the deepest scour relative to the bed sill.
