Study Of Settling Velocity And Carrying Capacity Of Nonuniform Fine Sediment

Non-uniform fine sediments’ movement rule is one of the basic questions of theSediment movement mechanics and many ports and reservoirs’ sediment issues belong tothese fine sediments, so the study on fine sediments has a large scientific and theoreticalsignificance and practical application.This article studies the natural alluvial non-uniformfine sediments of Three Gorges reservoir area and makes a experimental research on groupsettling velocity and sediment-carrying capacity.First of all, aiming at the defects and deficiencies of the existing experimental researchmethods, this paper proposes a experimental method of fine sediments’ group settlingvelocity. based on image gray and we independently develops a pilot system on finesediments’ group settling velocity. This paper based on the theory of the differences ofdifferent concentrations of mud water’s transmission indicates different concentrationsusing picture’s image gray and use the change of pictures’ image gray of asynchronousobserved value to reflect the variation of sediment’s concentration. to deduce the settingvelocity of sediments. Using this method, we run4groups of experiments with different initial sandconcentrations and use these experimental results to get a formula of fine sediments’ group settlingvelocity. This method is beneficial to the full observation of sediment concentrations inwater body and vastly reduce the disturbance to the water body in the experimental processand the operational process is easy；The disadvantage is that the control of the testconditions (especially light conditions which has a larger influence on the test results)requires further improvement and enhancement.Then, this paper uses two experimental assumes and methods to run flume test andcombines its study results of the setting velocity to analysis fine sediments’sediment-carrying capacity of flow. The first experimental assume and method is thattaking the critical point which is between the state of sediment completely scoured and afew fall silting as the critical point of sediment-carrying capacity of flow’s saturation runsseveral experiments with different depth、velocity、slopping. The second experimentalassume and method is that using turbidity meter measures the sediment’s concentration offlow under the condition of enough sediments in the bottom of water, when the sediment’sconcentration tends to stable, it tend to saturate.Comparing these test results with Zhang Ruijin formula, we find there a large difference between them, so we use multiple regression statistics fit a formula of thesediment’s concentration of flow which is match to this paper.Focusing on characteristics of fine sediments, this article proposes the correspondingtest methods and early insights of natural alluvial non-uniform fine sediments’ groupsetting velocity and sediment-carrying capacity of flow. The cognition and study ofnon-uniform fine sediments’ movement rule need more prototype measurements andfurther experiment study.