The Effects of Approaching Flow Angles on the Local Scour at Semi-Circular Piers

초록

In this paper, the effect of the approaching flow angles on the local scour at semi-circular piers, which are the typical piers in the rivers and large streams in Korea, was analyzed based upon the maximum scour depth. The pier models were obtained from San Gae bridge in the Bocheong stream which is a tributary in IHP experimental watershed in Korea. Four parameters, which are the flow depth, channel bed slope, pier skewness and opening ratio, were selected as the major parameters to investigate the effect of the approaching flow angles. Finally, for the maximum scour depth, three equations indicating multiplying factors for approaching flow angles are suggested based upon the Froude numbers. The suggested multiplying factors were compared with those suggested by Laursen and Toch, and Mostafa et al. In the low Froude numbers, the multiplying factors suggested in this paper are well agreed with the previous works. However, in the high Froude numbers, the multiplying factors suggested in this paper are larger than the previous works and bring the deeper scour depths compared to the previous works.