Análise de estabilidade de taludes com métodos de equilíbrio limite: Barragem de Rejeitos Laborrie, Distrito do Lourenço, Calçoene/AP

Abstract

This study aims to analyze slope stability using limit equilibrium methods applied to a tailings dam located in the Lourenço district, municipality of Calçoene, in the state of Amapá, Brazil. The structure under analysis, known as the Laborrie Dam, is one of the oldest legally operating tailings dams in the country. The research was based on field and laboratory tests conducted in 2020, including SPT (Standard Penetration Test), triaxial compression, consolidation, direct shear, and permeability tests. For numerical modeling, the GeoStudio software was used, enabling simulations with different geometries and operational conditions derived from soil identification studies and embankment geometry, including the critical full-reservoir condition documented by the cooperative overseeing the structure. Four classic slope stability analysis methods were applied: Fellenius, Janbu, Morgenstern-Price, and Spencer, allowing a comparison between the obtained safety factors (SF). To assess stability under critical conditions with the creation of a freeboard, simulations were performed for a 3-meter raise using the three known construction methods: centerline, downstream, and upstream. The results indicated that, under the dam's original condition, the safety factors suggest stability. For the critical condition hypothesis, the SF values decreased but remained sufficient when analyzing the downstream raise, thus meeting the minimum safety criteria required by regulations. The study reinforces the importance of geotechnical characterization for operational structures and contributes to the understanding of earth dam safety in Amapá.