Avaliação da Influência climática na estabilidade de taludes de solo não saturado sob regimes extremos da região semiárida: estudo de caso da Barragem Castro

Abstract

Earth dams located in semi-arid regions are subjected to climatic conditions characterized by prolonged dry periods interspersed with concentrated rainfall events, which directly affect the hydraulic behavior and slope stability of these structures. In this context, this study evaluates the stability of unsaturated granular slopes of an earth dam located in the Brazilian semi-arid region, considering the influence of climatic actions and reservoir water level fluctuations over time. The case study was developed using real data from a representative earth dam, with analyses performed for distinct hydrological years selected based on differences in rainfall regimes. The methodology was based on transient numerical modeling using the GeoStudio software package, with integrated application of the SEEP/W and SLOPE/W modules, enabling coupled simulation of unsaturated flow and slope stability. Hydraulic and mechanical parameters of unsaturated granular soils were adopted, including the soil–water characteristic curve, suction-dependent permeability, and shear strength parameters incorporating the effect of matric suction. The results show that the safety factor varies significantly over time, following reservoir water level oscillations and the hydraulic response of the embankment to rainfall events. A reduction in the safety factor was observed during periods of intense precipitation, associated with suction reduction and increased pore-water pressures, highlighting the importance of transient analyses for safety assessment. It is concluded that explicitly considering climatic conditions and unsaturated soil behavior is essential for a more realistic evaluation of earth dam stability in semi-arid regions.