Study of Ion Adsorption and Shear Strength of Red Clay under Leaching Action

Abstract

To study the soil-water effect of red clay, a leaching test is conducted by loading red clay into a soil column and collecting the leaching waste liquid periodically for analysis of the ion content and conductivity changes in the leaching waste liquid. After leaching and filtering, the soil is removed from the column and reconstituted as a straight-shear specimen for a straight-shear test. Ca2+, Mg2+, and SO42− ions increased and then stabilized in water samples as leaching time increased, while Na+, Cl−, and NO3− declined and then stabilized. Due to their presence in the leaching solution, Ca2+, Mg2+, and SO42− ions are initially adsorbed by the soil and then saturated by adsorption. In contrast, Na+, Cl−, and NO3− precipitate out of the soil due to the dissolution and ion exchange of the soil sample, thereby weakening their effects. Consequently, these ions appear to vary in various ways. The relationship between ion content in solution and conductivity has also been discovere, and the conductivity varies with the total ion charge in the solution. The angle of internal friction decreases as the leaching time increases, but the cohesion of the soil increases.