Determination and application of osmotic suction of saline solution in clay

Abstract

Osmotic suction affects the mechanical properties of the clay and exists as long as the solute is present in pore water of soil. Determination of osmotic suction of pore solution is significant for quantitatively explaining the mechanical behaviors of clay in saline solution. This paper aims to introduce a calculation method to determine the osmotic suction of saline solutions and the application of the osmotic suction to quantify the mechanical behaviors of clay in saline solutions. Osmotic coefficient as the bridge connecting ion concentration and osmotic suction was calculated by a simplified half-empirical equation and verified by published experimental data. Then the osmotic suctions were achieved using the calculated osmotic coefficients, and two filter paper methods were carried out to verify the calculated results. The consistency between the experimental results and the calculated ones proved the correctness of the proposed method for calculating the osmotic suction. A step further, the mechanical behaviors of clay in saline solutions were explained and quantified from the microscopic with the concept of microstructural effective stress and the macroscopic with the concept of modified effective stress, both related to the osmotic suctions.