Geotechnical Investigation for Ultimate Pit Slope Design: A Case Study of Kayad Mine, Ajmer, Rajasthan, India

Mining Engineering

ABSTRACT This research presents a comprehensive geotechnical investigation for the design of ultimate pit slopes at Kayad Mine, an underground zinc-lead operation in Ajmer, Rajasthan, India. The study integrates rock mass characterization using RMR and MRMR systems, kinematic analysis, limit equilibrium stability assessment, and slope monitoring design. Geotechnical data from six diamond drill cores were analyzed to classify host rocks (quartz mica schist, calc-silicate, granite gneiss) into three geotechnical domains. Results indicate fresh rock masses range from "Fair" to "Good" quality with RMR values of 58 and 76 for metasedimentary and intrusive rocks respectively. Recommended bench stack angles of 54° for metasedimentary rocks and 57° for intrusive rocks were determined for a 50 m bench stack height at FoS=1.2. Kinematic analysis revealed a 40% probability of toppling failure on the western wall. A multi-tiered monitoring system comprising prisms, robotic total stations, GB-InSAR, and extensometers is proposed with a comprehensive Trigger Action Response Plan. The findings provide a framework for safe and economic slope design applicable to similar deposits in the Aravalli-Delhi Fold Belt. Keywords: Ultimate Pit Slope, Rock Mass Rating, Slope Stability, Kinematic Analysis, Limit Equilibrium, Slope Monitoring, Kayad Mine

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