Room and pillar layout analysis for a Great Dyke of Zimbabwe deposit

ABSTRACT: The stability of room and pillar mining layouts is critical in underground hardrock mining, particularly in geologically complex environments such as the Great Dyke of Zimbabwe. This study evaluates the structural integrity of a proposed room and pillar layout at a depth of 200 m, considering stress and deformation distributions to enhance pillar stability and room support. A comprehensive drilling program consisting of 104 boreholes was conducted to characterise the ore deposit, ensuring a geotechnically informed approach to mine design. Numerical modelling was performed using LaModel, a boundary element method (BEM)-based tool that simulates stress and displacement distributions in mining excavations. The model was calibrated with site-specific geomechanical parameters to provide an accurate representation of load transfer mechanisms and pillar performance. The study examined spatial variation of induced stresses and deformations along predefined grid lines to identify potential instability zones. Findings indicate that significant deformations occur in mining rooms, while high stress concentrations are experienced on pillars, necessitating strategic optimisation of pillar dimensions and room support. Elevated stress zones suggest a risk of localised pillar overloading, requiring enhanced reinforcement strategies. The study proposes integrating real-time monitoring systems to validate numerical predictions and enhance pillar stability assessment.