Author(s): Pigozzi Diego; Gregoretti Carlo; Pontin Marco
Linked Author(s): Carlo Gregoretti
Keywords: Sediment transport; Initiation of motion; Rolling; Virtual work
Abstract: A model is presented to determine the initiation of the entrainment of bed particles in an unidirectional steady-uniform stream flow. The model concerns the analyses of equilibrium of a spherical particle resting on three closely and equal spherical particles of different radius and subject to the gravity, hydrodynamic, buoyancy and seepage forces. The analysis of the equilibrium is carried out by the virtual works principle undergoing the upper sphere to a rotation, without sliding, about an axis selected as the mean between two possible extreme ones to take in account the chaotic position of particles respect to the flow direction. The relative degree of exposure of a particle to the stream flow is introduced. A velocity distribution of low submergence flow is used and the theoretical depths predicted by the model are compared with the ones from previous experimental tests on the entrainment of sediment at high slopes with satisfactory results.
Year: 2007