Role of Grain Size Distribution and Pier Aspect Ratio in Scouring and Sorting around Bridge Piers

Several bridge piers were visited, and their scour hole was characterized into three zones: scour, transition, mound zones. The observed onsite sorting scouring patterns recreated through flume experiments with varying pier aspect ratio (1:1, 1:2, 1:4 1:6) sediment geometric standard deviation (σg). showed that maximum depth decreased non-uniformity; 52.7 mm, 20.2 16.6 mm are the respective of beds σg = 1.4, 2.5, 5.2. While has minimal effect on values, it noticeable effects shape asymmetry. location lowest point shifted further downstream as increased. number occurrences where is outside upstream cylindrical hemisphere zero (0) for (3) five (5) processes upstream-to-downstream propagation may explain gradual decrease in fines surface, well asymmetry confirming role combined grading bed material piers’ scour-forming process.