109 1. INTRODUCTION Underground mining environments often involve challenging geological conditions that demand advanced ground control strategies. Many ore deposits are encased in complex geology with faults, shear zones, or weak rock units that can compromise excavation stability. Water is another pervasive threat: inflows along fractures or aquifers can flood workings, destabilize rock, and halt production. Traditional support methods like rock bolts and shotcrete are essential but may be insufficient in extremely fractured or waterlogged ground (Hildreth et al., 2020). In such scenarios, injection and consolidation techniques have proven to be critical tools for ground improvement. These methods involve pumping specialized grout or resin materials into rock mass discontinuities, voids, or broken ground to fill cracks, bond loose fragments, and seal water pathways. By doing so, the rock mass is effectively strengthened and waterproofed, enabling safer and more predictable mining. Injection technologies have been used in tunneling and mining for decades. Highpressure grouting with microcement began as a technique to control water and stabilize ground in European mines in the mid-20th century (Barton & Quadros, 2019). Similarly, polyurethane resin injection was introduced in German coal mines in the 1960s to consolidate weak roof strata and has since become a standard practice for stabilizing fractured ground and stopping water inflows (Hildreth et al., 2020). Over time, the range of injectable materials has expanded to include ultra-fine cements, water-reactive foams, and fast-curing organo-mineral resins. These innovations have broadened the applicability of injections from civil tunneling projects into the realm of hard rock and soft-rock mining. Today’s underground mines extract a variety of deposit types (from narrow high-grade veins to massive porphyry orebodies and even evaporite or coal seams) each presenting distinct geotechnical challenges. For example, vein-type gold deposits often occur in highly fractured host rock with significant water inflows along faulted contacts. Massive base metal deposits (e.g., lead-zinc or copper) may require large openings or long hole stopes, raising concerns about wall stability and dilution. Block caving operations induce controlled rock mass fracturing on a large scale but must contend with subsidence and potential mud rushes if water and fines mix. Coal seams and other bedded deposits lie in comparatively weak sedimentary strata that can collapse if not adequately supported, especially under aquifers or gas pressures. While these scenarios differ, a common theme is that uncontrolled water and poor ground conditions can cause costly delays, safety incidents, and ore losses if not managed (Barton & Quadros, 2019). In this context, injection-based ground improvement is an increasingly vital component of mine design and operations. By incorporating pre-excavation grouting (ahead of development drives or shaft sinking) and post-excavation injections (to stabilize problematic areas or stop leaks), mines can significantly reduce geotechnical risk. Pre-injection of water-bearing zones can limit water inflow and improve rock quality before mining advances, making development more predictable (Barton & Quadros, 2019). Post-injection allows remediation of unforeseen conditions, such as sealing a sudden burst of water or consolidating a fractured pillar discovered during operations. Crucially, injection programs can be customized to the geological conditions: selecting appropriate materials and techniques to address the specific needs of each deposit and
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