以长江口细颗粒泥沙为样本进行环形水槽起动试验,给出了三组不同中值粒径泥沙的起动流速和临界起动应力,同时用湍动能法(TKE)估算不同含沙量水体的床面切应力,给出了泥沙起动过程中床面切应力与含沙量之间的关系。床面切应力随着含沙量的增加而增加,当含沙量达到某一浓度后,床面切应力增长缓慢,随着含沙量的再增加,床面切应力再次迅速增高,而不同中值粒径的泥沙,增长速度并不一致,说明泥沙对床面切应力的影响并不仅仅表现在含沙量上,粒径大小也是影响床面切应力的重要因子之一。
Sediment incipient motion experiments were conducted by an annular flume,using the sediment samples collected from Yangtze estuary. The incipient velocity and the incipient shear stress of three median grain size sediment groups are observed. The turbulent kinetic energy method( TKE) was used to determine the bed shear stress(τ),by evaluating variations in the suspended sediment concentration( SSC) within the water column. The bed shear stress increases with the increase of sediment concentration. When the sediment concentration reaches a certain concentration,the changing rate of τ slows down obviously. As the concentration increasing again,the bed shear stress grows rapidly with different growth rate attributed to different grain size. The results of the experiments indicate that SSC and grain size have strong influence on bed shear stress.