LAUSR

It is well known that the slope failure in unsaturated soil is the decrease in the matric suction, when the rain water infiltrates. However, the seepage mechanism and the stability of unsaturated soil slope have not been well established in geotechnical engineering. In this study, the suction profile and reliability index of saturated-unsaturated slope is studied at different rainfall condition with intensity in the range of saturated hydraulic conductivity of MH and CL soil. The finite element seepage model is uncoupled with slope stability model to calculate the reliability index at different time of long duration uniform rainfall. For CL soil slope, the reliability index is slightly changed during and after rain fall infiltration. For the MH soil slope the wetting front remains unsaturated up to a certain time of rainfall infiltration. After this time, the infiltrated rainfall reaches the ground water table and elevates it. The reliability index of the soil slope is thus reduced.