Influence of soil-atmosphere interactions and unsaturated soil properties on slope stability

¹ Federal University of Bahia, Department of Materials Science and Technology - Prof. Aristides Novis 2, Federação, Salvador, Bahia, Brazil
² Lund University, Lunds Tekniska Högskola, Solid Mechanics Division - Ole Römersväg 1, Lund, Skåne, Sweden

^* Corresponding author: smachado@ufba.br

Abstract

Results of coupled slope stability analysis performed on two urban slopes in Salvador-BA, considering suction variations due to soil-atmosphere interactions over the years of 2016 and 2018 are presented. Boundary conditions, unsaturated soil shear strength and hydraulic parameters were determined by surveying the local topography, analysing climatic and hydrological data, and gathering undisturbed soil samples from the slopes. Soil characterization, saturated and suction controlled triaxial tests and permeability, evaporation and soil water retention curve tests were performed. The simulation of the slope stability over time was performed using SEEP/W and SLOPE/W. A “soil-climate interaction function” and a modifier function were used as two distinct approaches to model the interactions between soil and the environment. The Vanapalli et al. (1996) [1] and Fredlund et al. (1978) [2] models were used to fit the cohesion versus suction curves. The most severe stability conditions were obtained in modelling considering the modifier function for soil-atmosphere interaction and Vanapalli et al. (1996) [1] model for slope 2 and the model of Fredlund et al. (1978) [2] for slope 1.