Suffusion of sand-clay mixtures under stepwise increase in hydraulic gradient

초록

Suffusion refers to the loss of fine particles within the soil matrix without any associated volume change, induced by hydrodynamic forces. This study investigated the suffusion of sand-clay mixtures through one-dimensional soil column experiments under a stepwise increase in hydraulic gradient (i), aiming to evaluate the critical hydraulic gradient (icrit) as a function of the size ratio between sand and clay, clay type, and ionic concentration. It was found that icritwas less than 0.1 for all sand-clay mixtures examined in this study. In addition, the lower peak concentrations of filtrated clay observed in sand-illite mixtures, compared to those of sand-kaolinite mixtures at the same level of i, suggest that illite particles are more susceptible to suffusion. Overall, the observed breakthrough curves, mass fraction of filtrated clay, volume of outflow, and total injection time presented in this study highlight the importance of considering clay type, sand-to-clay size ratio, and ionic concentration when assessing the suffusion behavior of clay-containing soils under a stepwise increase in hydraulic gradient. (c) 2026 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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