Evaluación geotécnica para analizar la estabilidad de taludes en una operación a tajo abierto

Abstract

Open-pit mining, although technically and economically viable, presents challenges in slope stability, where failure can cause severe economic, social, and environmental impacts. This study aimed to evaluate the stability of slopes in a mining operation through a comprehensive geotechnical investigation, including rock mass characterization, geomechanical property analysis, and numerical modeling. The methodology combined field inspections, installation of six geomechanical stations, and geophysical tests (240 m of seismic refraction and one MASW test), enabling the evaluation of stability at both bench and overall scales. Laboratory tests included unconfined compressive strength, point load, index properties, triaxial compression, and direct shear, to determine strength and deformability parameters. The geomechanical zoning defined two main areas: Zone 1, consisting of oxidized and altered sandstones of low quality (RMR 32–34, RQD 20–30, hardness R1–R2), and Zone 2, consisting of oxidized and altered sandstones regular quality (RMR 43–44, RQD 35–40, hardness R3), both influencing slope design. Although both zones are lithologically composed of the same oxidized sandstones with argillic alteration, the difference in hardness is explained by varying degrees of weathering, fracturing, and cementation. Zone 1 exhibits greater weathering, oxidation, and fracturing, which reduces its cohesion and mechanical strength, while Zone 2 retains a more intact structure, less alteration, and better cementation, resulting in greater relative hardness. The final design established single bench heights between 2.0 and 4.0 m and triple benches of 30 m, minimum berm widths of 4.0 and 11.0 m, and a reliable bench face angle of 59°. The analyses showed that wedge and planar failures have safety factors above the required minimums, confirming their stability. Numerical modeling verified that global safety factors exceed regulatory values, concluding that the slopes are stable and do not require additional support. Continuous geomechanical monitoring is recommended to ensure safety throughout the mining operation.