Critical Shear Stress of Cohesive Bottom Sediments

Abstract

The main purpose of this study is to obtain a simple critical shear stress function for cohesive soft bottom sediments. A series of experiments concerning threshold levels of mud transport and two series of tests of their rheological and setting properties were conducted to find some correlation among these indices. We defined two threshold levels for mud transport and divided muds into two groups by their characteristics (settling type, flow curve, resuspension behavior, etc.). In discussing the factors determining the characteristics of the two groups, we found that natural muds usually belong to the first group, in which the two critical shear stresses are given as a function of yield value τy1 (defined in paper) independent of material, following a new definition of threshold for sediment detachment from the bed. Finally, the correlation between this yield value and the final settling volume ratio is also discussed.