The critical condition for incipient sediment motion can be described either using flow parameters(e.g.flow velocity and bed shear stress)or sediment transport parameters(e.g.pickup probability and bedload transport rate),and relevant analyses can be done theoretically either by considering a single particle or a group of particles on the channel bed.At present,the critical conditions derived by considering forces acting on a single bed particle is difficult to apply due to a series of unknown coefficients.In comparison,if based on sediment transport rates,the critical condition can be quantitatively evaluated.However,this approach depends on what parameter is used for describing dimensionless transport rate.Being different from the Einstein number,the dimensionless transport rate W* is linked to the pickup probability,which can be taken as a constant for the incipient sediment motion,independent of the bed surface property(rough or smooth).With this consideration,the critical shear stress derived from measured bedload transport rates agrees well with the Shields curve.
关键词
泥沙起动/Shields曲线/起动概率/起动输沙率
Key words
incipient sediment motion/Shields curve/critical pickup probability/critical sediment transport rate
维普
万方数据