MAXIMUM LOCAL SCOUR DEPTH VARIATION AT BRIDGE PIERS

摘要

In this paper, the maximum local scour depth variation by interaction between bridge piers was examined through the experiments having five piers in the non-cohesive bed material in the experimental flume. In the experiments, the maximum distance of 25 times of the pier length and the maximum distortion width of 8 times of the pier width were utilized. Through the experimental studies, it was indicated that the local scour depths are severely affected when the interaction between adjacent bridge piers exists. In the low flow, which can be characterized as low Froude number, the maximum local scour depth is obtained when the piers are installed in the straight line in the flow direction without any distortion. However, in the high flow, which can be characterized as high Froude number, the maximum local scour depth is obtained when the piers are installed with some distortion widths from the flow direction. The local scour depth by interaction between bridge piers is changed depending upon the Floude numbers, the distance between piers, and the distortion width between adjacent bridge piers. The maximum scour depth increment of about 60% when the interaction between bridge piers exists is obtained compared to the single pier. Also, because the scour patterns are affected by the time variation, the maximum scour can be indicated in the different piers by passing time. It can be suggested that the maximum scour depth at bridge piers predicted by applying the existing equations should be increased in the case of interaction between bridge piers.