111 or weathered, there may be little solid anchor. Injection provides a means to bond and solidify the rock mass itself. By permeating fractures and filling voids with a solidifying material, injections create a “glue” that knits together otherwise disconnected blocks. Two main approaches are common: microcement grouts and two-component resins. Ultra-fine cement grout (with particle sizes small enough to enter fine fissures) can be injected under pressure to gradually fill a network of cracks, then harden into a cemented matrix. This has been used for example in a Western Australian gold mine where fractured cap rock above a stope was grouted to prevent a cave-in; the cement grout increased the rock mass strength and effectively created a stable beam over the void (Proudman et al., 2017). For more demanding conditions with moving blocks or where faster strength gain is needed, chemical resins like polyurea-silicate are selected. These resins can exhibit high early strength and some flexibility, making them ideal to stabilize rock in dynamic environments (e.g., squeezing ground or seismic-prone areas). A notable case involved a deep, hard-rock mine in Mexico, where a valuable ore block was bordered by zones of historic collapse and intensely fractured ground. Traditional bolting and shotcreting were deemed insufficient to secure the area. Instead, a carefully designed resin injection campaign was executed to consolidate the rock mass around and above the block before mining through it. The organo-mineral resin penetrated the fine cracks and cured rapidly, creating a continuous, bonded zone that effectively formed a protective arch around the ore. As a result, the mine was able to safely extract the entire block with no unplanned collapses or instabilities (Ferrenbach, 2025). This example underscores how targeted injections in weak or broken ground can significantly improve stability and enable mining of areas that would otherwise be left unmined due to geotechnical risk. Figure 2. Consolidation injections in an intersection of galleries. 2.3 Managing large voids and cavities: some underground operations encounter natural or mining-induced voids that need to be filled or stabilized. Natural voids include karstic cavities in limestone-hosted deposits and geodes in igneous rocks, which can flood with water and collapse unpredictably. Mining-induced voids include old stopes or drifts from historical workings, as well as broken rock zones created by caving methods. Leaving such voids unfilled can pose a collapse hazard or a source of air and water flow. Injection techniques provide solutions here through cavity filling foams and grouts. Highexpansion and lightweight urea-silicate foams can be injected to fill large volumes, forming a solid but relatively light support that occupies the space and prevents further
RkJQdWJsaXNoZXIy MTM0Mzk2