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Open-pit coal mining accounts for 93% of India's total coal production, playing a significant role in meeting the nation's substantial energy needs. The success of an open-pit mine hinges on maintaining the steepest and deepest slopes that remain stable over the mine's lifespan. However, slope failure is a complex issue influenced by numerous factors. In the context of openpit coal mines, the rise side highwall involves cutting through a rock mass containing various elements like an unconsolidated weathered mantle of sandstone, sandy clay, clay, carbonaceous shale and coal. Some opencast mines within the Godavari Valley Coal Field (GVCF), India have encountered significant pit slope failures. This paper uses a numerical modelling approach aimed at effectively assessing the stability of the rise side highwall, leveraging available geotechnical data from one of GVCF's largest opencast coal mines. The research investigates the impact of seven detrimental factors on slope stability, including dynamic loading due to blasting, employing a methodical One-Factor-At-A-Time (OFAT) approach. The study utilises Rocscience Phase2 version 9.0, a Finite Element Method (FEM) based numerical modelling software to gauge the sensitivity of each factor on the Factor of Safety (FoS). The numerical modelling results indicate that there is a linear decrease in FoS corresponding to the reduction in cohesion and an exponential increase in the FoS as the angle of internal friction rises. Furthermore, the analysis reveals significant impacts on the FoS due to groundwater and seismic loading from the blasting. This approach aims to comprehensively analyse and understand the intricacies of slope stability in the specific context of open-pit coal mining. [ABSTRACT FROM AUTHOR]

The geotechnical assessment, safe design and monitoring of highwalls is one of the major challenges in Indian open pit mines. The aim of opencast mines should be to attain steepest possible slope angle without compromising safety in order to maximize profits. Highwall stability is essential for economical and safe exploitation of mineral during open pit mining. Geotechnical investigations are required to quantify the properties of soils and rocks within the mining horizons. The required minimum safety factor for highwalls is 1.2. Highwall should be monitored during open pit operations. This paper addresses the main elements of pit slope failure, accident statistics, design, and monitoring and pit slope management and also the guidelines for safe design and monitoring of open pit highwalls in India. [ABSTRACT FROM AUTHOR]