A Discrete Fracture Network approach to rock mass characterization and assessment of rock fragmentation for cave mining.

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Building on the increasing use of Discrete Fracture Networks (DFN) models in both mining and civil engineering applications, the proposed research has two major inter-related topics, which could be developed in parallel. The first topic includes studying the relationship between fracture length and volumetric fracture intensity in an attempt to quantitatively define the relationship between these parameters and the rock mass natural fragmentation. It is expected that this initial work will have a significant importance in helping defining the scale at which geomechanical synthetic rock mass models need to be simulated to fully capture the Representative Elementary Volume (REV) of a naturally fractured rock mass. The second topic involves focusing on pre caving assessment and in particular on rock mass fragmentation, since the impact of poor or unexpected fragmentation upon cave operations represents a significant engineering and economics factor. Research to date has certainly contributed to demonstrate that DFN tools can effectively assist in the fragmentation assessment, primarily through providing a better description of the natural fragmentation of the in-situ rock mass. However, the evaluation of primary and secondary fragmentation is still being carried out using alternative methods mostly based on practical experience, attempting to describe these processes using empirically derived rules rather than a direct solution of the processes and mechanisms involved. It is believed that synthetic testing of DFN based rock mass models, by means of hybrid Finite/Discrete Element simulation of rock breakage, can be effectively used to better capture fragmentation mechanisms and develop an alternative approach to aid fragmentation assessment in mining and civil applications. The proposed approach would rely not only on the ability to fully capture the broader heterogeneity of the rock mass, but more importantly on the ability of determining a critical fracture intensity value at which the transition from intact massive rock mass to kinematically mobile rock mass occurs.