Abstract #

This paper presents a case study on the stability analysis of the dump slope at the Makardhokra-II open cast mine in Nagpur, India. The study focuses on evaluating the Factor of Safety (FoS) for the overburden dump (OBD) slope using GEO5 software, which applies the Limit Equilibrium Method (LEM). The analysis investigates various stability improvement techniques, including the use of cantilever retaining walls and gabion walls, to enhance the stability of the dump slope composed primarily of black cotton soil. The results indicate that while increasing the slope angle decreases the FoS, the introduction of retaining structures, particularly gabion walls, significantly improves stability.

Technical Relevance #

This document is crucial for geotechnical engineers and professionals involved in the design and analysis of slopes in open cast mining operations. The study provides critical insights into the challenges associated with managing dump slope stability in regions characterized by expansive soils, offering practical solutions for enhancing the safety and stability of such structures.

Target Audience #

The document is intended for geotechnical engineers, civil engineers, researchers, and professionals involved in mining operations and slope stability analysis. It is particularly relevant for those working in open cast mining environments where overburden dumps pose significant stability challenges due to the presence of problematic soils like black cotton soil.

Software and Methodology #

The stability analysis was conducted using GEO5 software, which employs the Limit Equilibrium Method (LEM) to evaluate the FoS for various slope conditions. The study examines different scenarios, including the natural slope without any retaining structures, the addition of a cantilever retaining wall, and the introduction of a gabion wall. The software applies three LEM techniques—Bishop, Fellenius, and Spencer methods—to calculate the FoS and determine the most effective stabilization approach.

Process Description #

The paper begins with a description of the Makardhokra-II mine site, emphasizing the geotechnical challenges posed by the extensive black cotton soil layer. The process description includes the collection and testing of OBD material samples to determine key geotechnical properties such as cohesion and angle of internal friction. The study then outlines the numerical modeling approach using GEO5 software to simulate the slope stability under different conditions, including varying slope angles and the use of retaining structures. The analysis also considers the economic feasibility of different stabilization techniques, comparing the costs of constructing cantilever walls versus gabion walls.

Main Findings #

The study finds that the stability of the dump slope is highly sensitive to the slope angle, with the FoS decreasing as the angle increases. The introduction of a cantilever retaining wall improves stability, but the construction cost is significantly higher compared to a gabion wall. The analysis shows that gabion walls are not only more economical but also provide adequate stability, especially in cases where the slope starts close to the top of the wall. The research highlights the importance of considering both technical and economic factors when selecting a stabilization method for dump slopes in open cast mines.

Practical Applications #

The findings from this study are directly applicable to the design and management of dump slopes in open cast mining operations. Engineers can use the insights gained to improve slope stability and ensure the safety of mining operations, particularly in regions with expansive soils. The study also provides valuable guidance on the use of retaining structures, suggesting that gabion walls offer a cost-effective and environmentally friendly solution for stabilizing dump slopes.

Limitations and Considerations #

The document acknowledges that the accuracy of the stability analysis depends on the quality of the input data, particularly the geotechnical parameters of the OBD material. Engineers should conduct thorough site investigations and consider local geological conditions when applying these findings to their projects. The study also emphasizes the need for continuous monitoring during mining operations to validate the model’s predictions and adjust the design as necessary.

Conclusions #

The paper concludes that the use of gabion walls offers a practical and cost-effective solution for enhancing the stability of dump slopes in open cast mines. While cantilever retaining walls provide slightly better stability, their high construction cost makes gabion walls a more attractive option, particularly in temporary mining operations. The study demonstrates the effectiveness of using GEO5 software for slope stability analysis, offering valuable insights for geotechnical engineers working in the mining industry.

Related Resources #

Further reading includes studies on the application of the Limit Equilibrium Method in slope stability analysis, research on the stabilization of dump slopes in mining operations, and case studies on the use of retaining structures in geotechnical engineering. Additional resources on the economic evaluation of stabilization techniques can provide deeper insights into optimizing slope management strategies in open cast mines.

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