Experimental Study On Deposition In Static Water Of Fine Sediment

The investigation on the flocculation characteristics of sediment and the rule of sediment movement is an important subject of sediment dynamics;It is of great significance for deep understanding of reservoir sedimentation,coastal beach development and port waterway maintenance.Currently,at the theoretical and practical aspects,many scholars have done a lot of research on sediment deposition in static water of fine sediments,but some problems remain unresolved.This paper regard sediment body of Wei he as sediment,The flocculation microscope images were analyzed with Using the IPP and the fractal theory.And make the calculation of the effective density of the traditional calculation floc simplified.At the same time,using the MATLAB with the calculation method of the dimension of the two-dimensional digital image box is to calculate the fractal dimension of the floc.From different initial sediment concentration and electrolyte to discuss density,porosity,fractal dimension and diameter of floc.What's more,From the macroscopic aspect,more comprehensive experimental study and discussion on the sedimentation process of fine granular cohesive sediment.Then considering that the majority of the actual water bodies contain cations,and their effect on the flocculation and sedimentation of fine sediment is significant.On the basis of Gang Qialuofu's velocity formula,the ion concentration parameters are introduced to fit out one more in the actual water Calculate the formula for flocculation.Draw the following conclusions:(1)When the initial sediment concentration is(50g / L,70 g / L)the effective density of flocs increased to decreased with the increase of sediment concentration.However,initial sediment concentration is(100g / L,150 g / L),the effective density of flocs showed a tendency to decrease to increase with increase of initial sediment concentration.(2)In the case of other conditions of the same change,the fractal dimension of the flocs is shown to increase to decrease with the increase of the electrolyte strength.(3)The flocculation process can be divided into two stages: flock sedimentation and flocculation sedimentation.Moreover,with the increase of sediment concentration under the same electrolyte condition,the flocculation sedimentation rate gradually decreases and stabilizes.(4)The effect of cationic valence on the settling velocity of flocs is much greater than that of electrolyte.(5)The effect of sediment particle size on flocculation sedimentation is closely related to sediment concentration,electrolyte strength and cationic valence.(6)The formula of flocculation velocity is more in line with the measured value.