Integrated risk-based design approach for wedge hazard in underground mining drifts

Structurally controlled rock instability is one of the most critical types of ground failure in underground excavations under low-stress conditions. Typical stability analysis approaches consider a series of simplifications related to the geometry of the rock discontinuities and the excavation. These methods cannot fully determine the probability of occurrence and size of wedges formed at the excavation walls, which is critical for quantifying the hazard associated with wedge failure in underground mines. This paper presents a comprehensive and systematic approach for assessing wedge formation and stability around underground mining excavations. The work considers the complexity of the structural regime using DFN modelling and the detailed 3D underground excavation profile obtained from surveying. The developed approach was successfully applied in an operating underground mine, enabling the estimation of the location and size of the most critical wedges and quantification of the risk associated with wedge formation. Determining the possible magnitude and location of formed wedges is invaluable information for designing drift geometry and rock reinforcement strategies. The DFN-based risk analysis was combined with economic metrics, providing a comprehensive risk analysis related to wedge failure at the underground mine. The developed approach contributes to optimizing ground support systems under low-stress conditions.