Stability Assessment of Vertical Remnant Pillars In Cut and Fill Mining Method with Numerical Modelling

Abstract

Cut and fill mining method involves extraction of orebody in horizontal slices in weak rock formations. The void created as a result of excavation is backfilled and vertical pillars are left at intervals if the overlying roof is weak. This method is advantageous in terms of ore recovery and safety, making it a preferred method for steeply dipping orebodies in challenging underground environments. These remnant pillars left intact plays a crucial role in supporting the overlying strata and protecting a safe environment for ore exploitation. The stability of these pillars is important since pillar failure results in catastrophic consequences including subsidence or even loss of lives. Hence, the pillar dimension is one of the important parameters which governs the stability of the overlying strata in cut and fill mining method. The present study focuses on the assessment of vertical pillar stability with 5 m × 5 m dimension left intact throughout the entire depth of orebody in cut and fill post pillar mining method considering three-dimensional finite element analyses. Based on the simulation results obtained from numerical modeling, it was found that the pillar dimension of 5 m × 5 m was stable enough for the considered geo-mining condition with factor of safety above unity. © 2025 Avestia Publishing. All rights reserved.