Research on Soil-water Characteristic Curve of Unsaturated Mixed-soil in Western Sichuan

The geological structure and climate conditions are complicated in the western area of Sichuan, the deformation or landslide damage of the non-saturated mixed-soil roadbed were often caused by the traffic load and rainfall infiltration. Engineering properties of unsaturated soil were closely related to the matrix suction. In order to investigate the effect of mineral composition of unsaturated mixed-soils and dry density on the soil-water characteristic curve in western Sichuan, soil-water characteristic curves of three typical unsaturated mixed-soils in western Sichuan were measured by filter paper method and pressure plate method under different dry densities. The macro phenomenon was analyzed to explore the influence mechanism of the characteristics of the mixed-soil by dint of microscopic characteristics. The results show that mineral composition has a significant effect on soil-water characteristic curves. The higher the content of hydrophilic minerals in the soil is, the greater the matrix suction will be, and the smoother the curve will be. On the contrary, when there is high quartz content and low clay content in the soil, the corresponding matrix suction is usually low. Under the same matrix condition, the larger the dry density is, the larger the soil water content can be. The effect of dry density on the soil-water characteristic curve increases with the decreasing water content. Van Genuchten (VG) model is used for fitting the mixed-soil water characteristic curve, and the fitting parameters are related to the particle size distribution and unsaturated degree. Hence, the fitting curves are in line with the experimental curves. The results can provide the theoretical basis for the analysis of the structure of saturated mixed-soil in Western Sichuan. © 2017, Editorial Department of China Journal of Highway and Transport. All right reserved.