Study of difference of local scour depthes at bridge piers under both steady and unsteady flows in rivers with fine sand beds

摘要

The experimental study of comparison of local scour depthes at bridge piers under both steady and unsteady flows in fine sand river beds is carried out in the paper. The result shows that the maximum local scour depth at bridge piers under unsteady flows is generally less than the balance depth of that from steady flows with equal flood peak discharges to the unsteady ones, but larger than the balance depth of that from unsteady flows with equal average flood discharges. The correlation of local scour depthes at bridge piers between steady and unsteady flows is established through the experiment, at the same time, calculation method for local scour depthes at bridge piers under unsteady floods in fine sand river beds is obtained.