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UBC Theses and Dissertations

The impact of fracture size distribution on primary fragmentation estimates in cave mines Cancino Martinez, Christian Felipe


Fragmentation estimation in cave mines is pivotal for optimizing productivity and ensuring operation safety. Accurate primary and secondary fragmentation forecasts facilitate efficient secondary breakage works and effective wet muck and mill throughput management. Advanced primary fragmentation estimation typically relies on Discrete Fracture Network (DFN) modelling, which generates three-dimensional representations of the persistent vein (when heavily veined) and fault networks within Synthetic Rock Mass (SRM) samples under expected caveback stresses (Garza-Cruz & Pierce, 2014). Recently, Pierce et al. (2022) introduced a predictive nomogram for primary fragmentation, accounting for various cave propagation factors (CPF) and fracture intensities (P₃₂). However, a limitation arises from the potential disparity in primary fragmentation estimates due to variations in underlying fracture size distributions among DFNs with similar fracture intensities. This research aims to deepen the understanding of the impact of fracture size distribution on primary fragmentation estimates and exemplify its significance by contrasting primary fragmentation estimates for different mean fracture sizes under identical fracture intensity. The goal of evaluating selected DFN parameters is to identify more robust parameters that could enhance existing nomograms beyond volumetric fracture intensity considerations. Mapping data recommendations are also proposed based on observed trends in this study, particularly regarding fracture termination data. The primary objectives of this study include confirming the significant role of fracture size distribution in primary fragmentation estimates through numerical simulations of the caving process and identifying state-of-the-art DFN geometric parameters for improved three-dimensional representations. Furthermore, a secondary objective of this study is to investigate the influence of hydraulic fracturing (HF) on primary fragmentation under specific geomechanical conditions. This comprehensive research aims to provide valuable insights for optimizing cave mining practices by considering enhanced geometric DFN parameters, mapping fracture termination data, and examining the influence of HF on primary fragmentation.

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