On sediment incipient motion of marine cohesive sediments with different bulk densities

• Published in: Geomorphology (Amsterdam, Netherlands) Vol. 441; p. 108918
• Main Authors: Li, Shouqian, Zhu, Mingcheng, Huang, Wei, Zhu, Hao, Zhang, Rui, Lu, Yongjun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.11.2023
• Subjects: Bulk density; Cohesive force; Fine sediment; Sediment incipient motion; Shields curve; Bulk density; Shields curve; Fine sediment; Cohesive force; Sediment incipient motion
• ISSN: 0169-555X; 1872-695X
• DOI: 10.1016/j.geomorph.2023.108918

This paper aims to methodically examine the incipient characteristics of natural marine fine sediment with particle size less than 0.012 mm for a variety range of bulk densities. Theoretical derivation and experimental data analysis are appropriately combined to explore the effect of bulk density on the inter-particle cohesive force and to deduce the incipient shear stress (ISS) of fine sediment. Under the same particle size condition, the achieved results indicate that the ISS of sediment intensifies with the growth of the bulk density. In addition, the larger the bulk density, the faster the increase rate, revealing a power exponential growth trend. The ISS of sediment also magnifies with the reduction of the particle size under the same bulk density condition; however, as the particle size decreases to 0.007 mm, the ISS of sediment would no longer vary. The influential factors on the cohesive force, including intermolecular gravitational force, film water pressure, and bulk density, are thoroughly analyzed, and a rational expression for the cohesive force is also proposed. The modified shields parameter represents the ratio between the sediment driving force and the stabilization force (e.g., gravitational and cohesive forces) and is still a function of the sediment Reynolds number. The modified shields curve still follows the shape of the original shields curve and satisfies both cohesive and non-cohesive sediment conditions but with differences in the form of shields parameter. •Focus on sediment incipience with particle size less than 0.012 mm for various bulk densities•Collect 77 sets of Chinese offshore fine sediment initiation flume experiment data•Propose an inter-particle cohesive force expression by considering the role of bulk density•Derive a modified shields curve suitable to both cohesive and non-cohesive sediment