Abstract
This study examines slope stability at the Ula Ulo Placer gold mine in the Adola Belt, Guji, southern Ethiopia, where open-pit mining enables flexible mineral extraction but presents significant stability concerns. Frequent slope failures have disrupted operations and delayed production. This research aims to evaluate and improve the stability of the open-pit excavation through an integrated approach combining field investigations, laboratory testing, and numerical modeling. Fieldwork included detailed slope geometry and orientation measurements, in situ testing, and soil and rock sampling for laboratory analysis. Stability assessment was performed using both the Limit Equilibrium Method (LEM) and the Finite Element Method (FEM) via Slide 2D (v6.0) and Phase2 (v8.0) software. The variables analyzed included bench angle, width, overall slope angle, and geotechnical properties under drained and undrained conditions. The analysis indicated that a 40° slope was unstable and unsuitable, while a 30° slope provided high stability but involved excessive excavation. A 35° slope was found to be the most practical solution, offering an effective balance between structural safety and excavation requirements.