Three-Dimensional Spatial Stability Analysis of the Fundão Dam

The failure of the Fundão Dam has been previously studied using two-dimensional approaches. The original investigation findings did not point to mechanisms of slope instability as the causes of the disaster. However, the complex shape of the dam and its concave and convex regions were not considered due to the limitations of the analysis tools employed. This paper presents two-dimensional (2D) and three-dimensional (3D) analyses that are more rigorous and better suited for the Fundão Dam geometry. Slope stability analyses were accomplished using the general limit equilibrium method (GLE). Critical slip surfaces were searched in 2D and 3D across the entire dam face. Drained shear strength parameters led to factors of safety (FS) that would indicate fairly stable conditions, with the lowest FS being 1.744. Values close to 1.0 were obtained considering undrained conditions. The 3D values of FS were very close to the 2D values, but with noticeably higher variations near the concave and convex regions. This leads to the conclusion that the dam shape near the setback region requires closer examination by means of 3D analyses, enabling the identification of critical zones.