Experimental model of rainfall induced slope failures in compacted clays.

摘要

A series of experiments were conducted on high plasticity clay to determine a relationship between void ratio, seepage pattern, intensity and duration of rainfall and clay slope stability. Rainfall represents the development of perched water table, increasing the main groundwater level and soil erosion due to concentrated water flow. It results in an increase in pore water pressure or a reduction in soil matric suction and loss in shear strength of soil. The decrease in shear strength entails to a point where the equilibrium can no longer be sustained in the slope and then a failure occurs. Seismic effect is also a cause to triggers landslides; however, this study is limited to the assessment and evaluation of the effect of induced rainfall and the increase in pore water pressure on slope stability analysis. A common soil in Southern California was selected to perform the experiments and physical models consisted of placing the collected soil into a Plexiglas container at the void ratio of 0.89 at different inclinations and introduction of target rainfall with a rain simulation system in order to measure the seepage rate and pattern, and change in moisture content, degree of saturation and matric suction with time. Results showed that seepage velocity decreases with the inclination of slope and the slope of wetting front is gentler than the soil slope in clays. Pore water pressure does not increase uniformly over the entire slope and it depends on the seepage rate of water due to the anisotropic hydraulic conductivity of clays.