Salt-Driven Dynamic Regulation of Permeability in Dispersive Soil: A Macroscopic and Microscopic Investigation

DOI: https://doi.org/10.62517/jes.202602212

Author(s)

Junting Liu*

Affiliation(s)

Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education, Beijing University of Technology, Beijing, China *Corresponding author

Abstract

Dispersive soil is a special type of soil widely distributed around the world, and its susceptibility to erosion upon contact with low-salinity water poses significant challenges to hydraulic engineering. The understanding of its seepage characteristics, particularly the role of salt in regulating permeability, remains limited. In this study, typical dispersive soils from Da’an City were collected, and remolded specimens with varying salt contents (0%, 0.3%, 1.0%, 1.5%, and 2.0%) were prepared. Variable-head saturated permeability tests were conducted in conjunction with scanning electron microscopy (SEM) observations to investigate the time-dependent permeability behavior and the underlying microstructural mechanisms. The results show that the permeability coefficient of dispersive soil exhibits a decreasing trend over time, with the attenuation concentrated in the initial stage of seepage. Salt content is positively correlated with the initial permeability coefficient, with the high-salt group showing a considerably higher initial permeability than the salt-free group. However, this enhancing effect diminishes significantly with seepage duration, and the difference between groups narrows substantially by the second day. SEM observations reveal that medium-salt conditions (1.0%–1.5%) facilitate the formation of a stable flocculated structure that maintains favorable permeability, whereas high-salt conditions (2.0%) produce a loose flocculated structure that undergoes degradation upon salt leaching, leading to a rapid decline in permeability. The findings demonstrate that salt dynamically regulates the permeability of dispersive soil by controlling microstructural evolution, providing a theoretical basis for the long-term performance assessment of saline dispersive soil under engineering seepage conditions.

Keywords

Dispersive Soil; Salt Content; Permeability Coefficient; Microstructural Evolution; Seepage Characteristics

References

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