Mohammad Vaghefi

This research examines the influence of peak time, flood duration, and pier position on the variations in scour pattern and the greatest depth of scour cavity surrounding a single pier protected with a collar. The study encompasses a flow velocity range spanning from incipient motion conditions to mobile bed conditions. The findings demonstrate that the implementation of a collar not only reduces the dimensions of the scour cavity surrounding the piers but also alters the location of the greatest depth of scour cavity. On average, the utilization of a collar at 60°, 90°, and 120° positions during four flood durations resulted in respective reductions of 40%, 60%, and 45% in the average scour cavity volumes surrounding the pier. Results further indicate that the collar successfully reduced the greatest depth of scour cavity, volume, and area surrounding the pier in over 95% of the conducted tests.