Stability of unsaturated soil slopes subjected to external load and rainfall

The aim of this study is to investigate the effect of the amount of the external load and failure form for the slopes of unsaturated clayey and alluvial soils. Also, the impact of the rainfall on the stability of these slopes was also studied. Laboratory physical model was designed as a box with dimensions of 1580 × 1400 × 2000 mm. Heavy rainfall with the intensity of approximately 10 and 5 mm/hr with duration 16 and 8 h for soil A and B, respectively, was imposed. Soil B was very sensitive to the changes in the total suction comparing with soil A. The effect of rainfall reduced the load capacity from 510 and 359.8 to 183 and 11 kPa of soil slopes A and B. Therefore, a reduction in load capacity of 64 and 97% was obtained.