A laboratory study of stratified characteristics of cohesive sediment movement in the lower energy conditions

摘要

Cohesive sediment is a major component of clay. Its erosion and movement has a significant impact on the soil environment. Moreover, cohesive sediment is an important part of the sediment of lakes and oceans, and its movement and transportation also have a crucial influence over dispersion of pollutants in water. Open channel flume experiments were carried out to study the characteristics of cohesive sediment movement; simultaneously the velocity and sediment concentration vertical profile was investigated. The experimental results indicate that under the conditions of suitable hydrodynamic velocity and sediment concentration, a special-shaped sediment flow, stratified movement, takes place in the flume. Its formation and features are closely related to fluid parameters and sediment concentration. Its velocity distribution shows a V-shaped pattern falling forward. At the corner of V, the maximum velocity is vertically located in the middle of the flume. The concentration distribution is vertically stratified into three discrete layers on whose interfaces the concentrations change suddenly. To form lamination movement, different hydrodynamic conditions are required under different sediment concentrations. When the concentration increases, the corresponding flow intensity also increases.