Experimental Study on the Angle of Repose of Submerged Cohesive Sediments

Abstract

The angle of repose (AoR) of sediments is an important parameter in the hydraulics of sediment transport. This study investigated the AoR (ϕ) of submerged cohesive sediments using a tilting plane. The results indicate that the yield stress and particle size are factors that have major influences on the AoR. For specific sediments, sin(ϕ) increases linearly with increasing yield stress. For a certain yield stress, the AoR increases with increasing median grain size. Meanwhile, the effect of the yield stress on the AoR is significant for the cohesive sediments and becomes progressively weaker with the increasing median grain size. A simple and reliable empirical formula that includes a rheological term and a gravity term is proposed to calculate the AoR of submerged cohesive sediments. Furthermore, a series of vibration tests was designed and performed with the sediment samples to explore the effect of mechanical vibration on the AoR. The results show that the mechanical vibration can significantly fluidize the submerged cohesive sediments, which can lead to a significant decrease in the AoR.