Estudo da influência da distribuição granulométrica sobre o transporte e resistência em canais erodíveis.

Abstract

The principal objective o f this work is to verify the influence of sediment size distribution about transport and resistance in alluvial channels. Data were gathered in experiments using a completely automatic recirculation channel with three sediment mixtures, uni modal and log-normal, that had the same median diameter D 5 0 (0,38 mm) and different size distribution. It was also postulated the possibility there be a representative diameter, different than median diameter, for each size distribution studied. For this purpose were selected the following transport equations: Einstein (1950), Bagnold (1966), Laursen (1958) and Yang (1973), to calculate the sediment transport rates. Taking into account the transport and resistance to the flow, the non uniform mixtures, in identical flow conditions, shown smaller transport rates and larger resistance values than the most uniform mixture. The results got with the transport equations, when were used different diameters than median diameter, didn't differ too much than the results with D50, it means that only small adjustment in the transport rates were obtained.