Document Type : Research Article
Authors
1
Visiting Professor, Department of Mining and Metallurgical Engineering, Yazd University, Yazd, Iran
2
Faculty of Mining Engineering and Metallurgy, Yazd University
3
Department of Mining Engineering, Islamic Azad University, Sirjan Branch, Sirjan, Iran
10.22034/anm.2026.22675.1660
Abstract
The instability of slopes in open-pit mining operations poses significant challenges to mine safety, environmental sustainability, and overall economic performance. The stability of pit walls is primarily governed by factors such as slope configuration, the integrity of the rock mass, and geological heterogeneity. Determining an appropriate overall slope angle (OSA) is a critical aspect of mine design, as it directly influences both operational safety and cost efficiency. Typically, pit walls are modeled with planar cross-sections, where the inter-ramp segments are defined by uniform angles. However, geological layering often introduces lithological diversity and spatial variability in rock strength, which must be incorporated into the design process. This research employs numerical simulation techniques to assess slope stability under realistic geological conditions, focusing on how variations in OSA affect the safety factor. The modeling integrates actual mine features, including lithological contrasts, rock property fluctuations, and true slope geometry. In this research, eight slope configurations were analyzed, corresponding to overall slope angles of 31°, 33°, 35°, 36°, 38°, 40°, 45°, and 48°, which were selected to represent a realistic range of design alternatives, from conservative to more aggressive geometries. The results demonstrate that slope angles in the range of 31°–36° consistently maintain safety factors above 1.45, with 35° emerging as the most practical design angle due to its balance between geotechnical reliability and economic efficiency. In addition, parametric sensitivity analyses revealed that elastic properties (poisson ratio) exert only minor influence on slope stability, whereas plastic parameters (cohesion value) have a dominant effect, significantly altering the safety factor. Overall, the study highlights that adopting a slope angle of 35°–36° provides a technically sound and economically advantageous solution for mine planners. The findings emphasize the importance of incorporating both geological heterogeneity and mechanical property sensitivity into slope design to ensure long-term stability and operational efficiency.
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