Author(s): R. Lanca; C. Fael; A. Cardoso
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Keywords: Local scour; Relative sediment size; Cylindrical pier
Abstract: Experiments on local scouring around cylindrical piers were performed in steady clear-water conditions to investigate the effect of sediment size, D50, on equilibrium scour depth, d se. Thirteen experiments, run for 7 to 13 days, were carried out. The dependence of the normalized equilibrium scour depth, ds e/D p, on the relative sediment size, D p/D50, was identified, corroborating the findings of Sheppard et al. (1995; 1999; 2004). Contrarily to consecrated literature and associated practice, it was observed that the normalized equilibrium scour depth decreases with the relative sediment size, for Dp/D50 > ～100. This effect is possibly one of the causes of frequently reported over-prediction of scour by formulas established on the basis of laboratory studies, where frequently Dp/D50 < ～100.
Year: 2011