| Summary: | A coupled DFN-DEM approach was used to evaluate the anisotropy of rock mass mechanical compressive strength (UCS) at Representative Elemental Volume (REV) at the feasibility stage of an open pit mining project located in Nunavut Territory in northern Canada. The paper presents modelling work performed to define the rock mass UCS based on field data and on laboratory testing results. In particular, the influence of the in-situ rock mass structural properties variations on the rock mass UCS is studied. To begin with, a discussion is presented on the difficulty to account for the anisotropy of the rock mass UCS at engineering scale. Coupled DFN-DEM modelling was shown to be useful although still rarely used mainly due to computing time limitation. In this paper, the modelling workflow is outlined. DFN modelling results are presented - several DFNs were modelled to fully represent the spectrum of possible structural regimes at the site. The DFN-DEM calibration process for simulating rock mass samples at REV size is also presented. DFN-DEM models were created for all generated DFNs – representing the observed spectrum of the structural rock mass properties. The rock mass UCS was evaluated for all samples and the anisotropy of the rock mass UCS was then calculated. The results suggest that for this mining site, the rock mass at REV size is strongly anisotropic. Furthermore, they suggest that the rock mass structural variability significantly affects the rock mass anisotropy. The results not only highlight the possibilities associated with DFNDEM modelling in characterizing rock mass anisotropy at the engineering scale, they also provide a systematic way to assess the variability in rock mass properties anisotropy for engineering works.
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