ABSTRACT
Unsaturated slopes fail during rainy periods especially because of the increase in the water pressure in the soil, which causes the reduction in the effective stress on slopes and the reduction in the shear strength of unsaturated soils. A research conducted on an unsaturated slope in São Paulo, SP, Brazil, measured on a daily basis the precipitations, the groundwater level and the water pressure up to 3.0 m depth, during eight months. Laboratory and “in situ” tests provided information about the characteristics of the soils composing the experimental slope. Analyses of the slope stability were performed for the dates when the maximum and minimum water pressures were recorded during the monitoring period. The results of the monitoring were satisfactory considering that the tensiometers installed in the experimental area presented readings coherent with the precipitations. The results of the stability analysis have shown variations on the landslide factor of safety as an effect of seasonal variations of the water pressure.
