Shear stress for initiation of motion of median sized sediment of no uniform sediment mixtures

Critical shear stress of median sized sediment of nonuniform sediment mixtures utilizing experimental data is studied in the paper. Four sediment mixtures with varying gradation and median size are used in the experiment. The critical shear stress of median sized sediment of the four sediment mixtures are found lower than the values obtained from the Shields’ diagram. The reason may be due to the effect of mixture sorting and efforts have been made to relate critical shear stress with mixture sorting. An empirical relation is developed by rearranging the dimensionless parameters of grain Reynolds number and mixture sorting. A formula is derived for the computation of critical shear stress of median sized sediment of nonuniform sediment mixtures by regression technique using with the experimental data and data available in the literature.

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