http://www.vliz.be/imisdocs/publications/ocrd/267179.pdf

Erosion of mud/sand mixtures

The initiation of motion of consolidated cohesive sediments under a unidirectional flow of clear water was studied. Experiments were performed in a flume‐tunnel capable of providing a bed shear stress up to 26 Pa and a velocity of 3.5 m/s, 3 mm above the bed. Samples were prepared in a specially designed press using a carefully controlled consolidation procedure. Critical shear stress and velocity were found to increase with compressive strength, vane shear strength, plasticity index, clay content, and consolidation pressure.

Cohesive Material Erosion by Unidirectional Current

......ii ACKNOWLEDGEMENTS.......iv DEDICATION..........v TABLE OF CONTENTS.......vi LIST OF TABLES ..x LIST OF FIGURES .....xii NOMENCLATURES .....xvii

Time development of local scour at a bridge pier fitted with a collar

This paper presents the results of a laboratory study undertaken to examine the effect of hydraulic variables on the scour of a cohesive soil produced by submerged plane turbulent wall jets. The velocity and thickness of the jet were varied in tests with one cohesive soil in part to determine if repeatable scour experiments by these jets could be performed in cohesive material. Measurements were taken of the scour hole profiles at the asymptotic or equilibrium state of scour, including the maximum depth of scour, the location of the maximum scour depth, and the length of the scour hole. Dimensional analysis is used to show that the scour hole dimensions at asymptotic state can be expressed as a function of the velocity at the nozzle, the density of the eroding fluid, the nozzle thickness, and the critical shear stress of the soil. The scour hole profiles are shown to scale with the maximum depth of scour and the distance from the nozzle where the scour is half the maximum scour depth. Observations of the ...

Scour of a cohesive soil by submerged plane turbulent wall jets

The results of an experimental study on scour under submerged circular vertical jets of water in cohesionless and cohesive sediments are presented. The difference between scour patterns in cohesionless and cohesive sediments is identified. In cohesive sediments, the variations of maximum depth and volume of scour have been studied with respect to the percentage of clay content, dry density, antecedent moisture content, etc. Empirical relationships have been proposed for the maximum depth and volume of scour for both nonplastic and plastic cohesive sediments. The range of data for the applicability of the proposed relationships is specified.

Influence of cohesion on scour under submerged circular vertical jets

This study evaluates the effect of some basic properties of clay-minerals mixed with cohesionless soil on scouring at the toe of a spillway Scouring was analyzed by the concept of incipient motion of the soil particles Experiment was performed to determine the influence of the clay-minerals (Kaolinites) and its compactness on the rate of volume of scouring It was assumed that seepage does not exist at the toe of the spillway and the characteristics of the flow is submerged Depth of the approaching flow at apron “a” and reference velocity “U” were kept constant throughout the experiment The results show that factors affecting scouring of cohesive bed downstream of a spillway include: flow characteristics, soil properties, fluid properties and boundary conditions Also when the rate of flow is finite, there is a limit to the extent of scour

Chin-Lien Yen

Papers

Scouring of cohesive soils