Rheological Properties of Bed Sediments Subjected to Shear and Vibration Loads

Abstract

The rheological properties of river and seabed sediments are important to describing the interactions of the currents and waves with the bed. This paper presents the findings from a study of the rheological properties of both sandy and cohesive (kaolin and mud) bed sediments under shear and mechanical vibration loads. It was found that the rheological properties of the sediments depended not only on the magnitude of the shear load but also on its duration. The sandy and cohesive sediments exhibited shear thinning and thixotropy for shear speeds greater than 1 revolution per minute, whereas the cohesive kaolin and mud exhibited antithixotropy for shear speeds lower than 1 revolution per minute. High-frequency vibration loads also significantly reduced the viscosity of the sediments, with the magnitude of the reduction increasing with the frequency of the vibration. The kaolin and mud were also fluidized by the vibration, and their recovery required a longer time compared with the sandy sediment. Some potential applications of these observations are highlighted in this paper.