Experimental study on incipient condition of fluidized bed sediment in oscillatory

SKLOE, CISSE, School of Naval Architecture, Ocean & Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

^* e-mail: yugl@sjtu.edu.cn

Abstract

In this paper, the incipient condition of the fluidized bed sediment with different sizes and water contents were experimentally studied in an os- cillatory tunnel made of acrylic boards. One-hundred experimental runs were performed with sediment samples by varying the yield stress to determine the relationship between the critical condition of incipient motion and the rheolog- ical properties of the cohesive sediments. Experimental results showed that the yield stress of the bed sediment decreased as the fluidization level increased. When the yield stress is no longer changed, the bed sediment was considered completely fluidized. In oscillatory flow, the critical shear stress decreases with the increase of fluidization level. When the bed sediment reaches the full flu- idization state, the critical shear stress of the bed sediment at the bottom re- mained constant. For cohesive sediments, in the case that particle size and bulk density were known, the relationship between the yield stress and the critical shear stress was analyzed, and the incipient condition of the cohesive sediment under oscillatory flow action was determined.