Impacts of Salinity and Consolidation on the Microstructure and Erosion Threshold of Cohesive Sediment

Juan, Jorge San; Wei, Guanju; Yang, Judy Q.

doi:10.1002/essoar.10511471.1

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“…The raw images of the clay surface during the erosion experiments, flow measurements, and series of the structural-similarity index to identify the erosion threshold have been deposited in The Data Repository for the University of Minnesota and are available at San Juan et al (2022aJuan et al ( , 2022b.…”

Section: Data Availability Statementmentioning

confidence: 99%

Impact of Salinity on the Erosion Threshold, Yield Stress, and Gelatinous State of a Cohesive Clay

San Juan,

Wei,

Yang

2024

JGR Earth Surface

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Clay is the main component that contributes to sediment cohesiveness. Salinity impacts its transport, which controls the electrochemical force among the sediment grains. Here, we quantify the impacts of salinity on the erosion threshold, yield stress, and the microstructures of a fluorescently labeled smectite clay, laponite, by combining flume experiments, rheometer measurements, and macro‐ and microscopic imaging. We show that the critical shear stress for clay erosion, τb,crit, increases by one order of magnitude with increasing salinity when salinity <1.5 ppt and slightly decreases when salinity >1.5 ppt showing a weaker dependency upon salinity. We further show that the yield stress, τy, of the clay remains roughly a constant at salinity less than 1.5 ppt and decreases by over one order of magnitude at salinity larger than 1.5 ppt. This change in the dependency of τb,crit and yield stress on salinity corresponds to a change in the gelatinous state of clay, from gel‐like structures to phase‐separated structures as salinity increases. Our results provide a quantitative characterization of the dependency of clay erosion threshold and yield stress on salinity and highlight the importance of the clay gelatinous state in controlling clay transport.

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Section: Data Availability Statementmentioning

confidence: 99%