Overburden (OB) dump stability is a critical geotechnical concern in opencast mining operations, directly influencing operational safety, production continuity, and environmental sustainability. Improper dump geometry, inadequate geotechnical characterisation, and simultaneous mining–dumping operations may significantly increase the risk of catastrophic slope failures. This study presents a comprehensive numerical evaluation of OB dump slope stability at the Lalmatia Opencast Project, Rajmahal Coalfields, India. A parametric analysis was performed using limit equilibrium techniques implemented in SLIDE software to evaluate the influence of slope angle, bench height, and bench width on factor of safety (FoS). The overburden material was modelled as homogeneous dry soil with experimentally determined shear strength parameters. Results indicate that slope angle is the most influential geometric parameter affecting stability. FoS decreases significantly beyond a slope angle of 30°, whereas bench width has a negligible influence within the investigated range. An optimum dump configuration was identified considering both safety and economic feasibility. The findings provide practical design recommendations for safe dump construction in similar geotechnical environments.
Sumeet Kishore (Thu,) studied this question.