Study on Permeability of Clay under Saline Environment Change and Permeability Prediction Considering Electrochemical Characteristics

Abstract

A continuously changing saline environment can lead to changes in the pore structure and the permeability of soils. Studying and establishing the theoretical relationships among factors such as ion concentration, mineral species, pore characteristics, and hydraulic conductivity can provide practical information for geotechnical engineering. For this matter, this paper designed sequential soil permeability experiments with different ion concentration NaCl solutions to study the influence of saline environment change on the permeability of different clayey soils. Meanwhile, an improved Kozeny–Carman equation (EDL-KC) considering the electrical double layer and pore structure was derived, and its applicability was comparatively analyzed. The experimental and theoretical analysis results showed that seawater erosion changes the pore structure of clayey soil composed of kaolinite or illite and reduces its permeability; a mineral composition-related critical ion concentration exists for soil permeability to first decrease and then increase with the growth of the ion concentration. Compared with the KC equation, the EDL-KC equation was found more suitable for predicting the permeability of clayey soil, of which the prediction error was mostly within the two times range.