Fitting models for soil-water characteristic curve of total and matrix suctions of Yili loess

The Yili loess of Xinjiang is characterized by strong collapsibility and high soluble salt content. For describing the suction parameters in the stress state of the unsaturated soils, both the total and matrix suctions should be taken into account. Therefore, the soil-water characteristic curve (SWCC) tests on Yili loess with different salt contents are carried out by using the filter paper method. The total and matric suctions of Yili loess with different salt contents are measured. The solution concentrations of samples with different salt contents are calculated. Additionally, the effects of salt content on the collapsibility are analyzed. Based on the Gardner model, fitting models for SWCC of total and matrix suctions for Yili loess which can consider the influences of soluble salt content are proposed. The test results show that the salt content has a certain influence on the matrix suction of Yili loess of Xinjiang, and it has a great effect on the total and osmotic suction. The solution concentration in the soil samples increases with the increase of the salt content, and there is a linear relationship between the total suction and the concentration. With the increase of soluble salt content, the collapsibility of soil samples increases obviously. The proposed SWCC models can consider the influences of soluble salt content, and they can describe the variation of the total suction and matrix suctions for Yili loess with water content and soluble salt content.