1919 show trial results confirming acoustic sensitivity to rockfall impacts and trajectory estimation through sensor fusion. 2.3 Sub-surface geotechnical monitoring using distributed fibre optic sensing Distributed fibre-optic sensing provides a powerful platform for monitoring seismic activity, strain, and temperature in both underground and surface mining environments. These systems deliver continuous, real-time measurements along the length of low-cost optical fibre, enabling high-resolution geomechanical analysis. Deployment typically involves borehole grouting or shallow back-filled trenches. Microseismic monitoring using fibre optics has proven effective in revealing strata behaviour during longwall retreat, offering valuable insights into deformation and failure mechanisms. Similarly, strain sensing in sub-level cave operations improves understanding of stress redistribution and ground response. Fibre-optic systems has also recently been demonstrated to support microseismic monitoring in block cave mines, providing critical data for hazard prediction and operational safety, including caving and fracture zone and strata delamination analysis (Figure 3). Figure 3 – The distribution of fractures in cross-section. The strata with different fracturing behaviours are highlighted by dashed eclipse (Duan et al., 2025a). 2.4 Borehole imaging while drilling for geotechnical structures Several geo-sensing technologies show strong potential for detecting structural features in rock masses to support geotechnical design. For fractures intersecting drill holes, traditional tools such as optical televiewers (OTV) and acoustic televiewers (ATV) remain the most effective. However, identifying fractures that do not intersect boreholes (particularly those sub-parallel to drilling) requires alternative approaches.
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