Abstract

Geometric Discrete Fracture Network (DFN) models are constructed in this research project, where limited and insufficient field structural data were exploited statistically in terms of observed parameter distribution at the mine-scale perspective. The construction of a DFN model employing a disaggregate technique was suggested by descriptive statistics of intensities (P10), orientation and length. The DFN model was validated by field data. The calibrated DFN model was then exported in a two-dimensional Distinct Element Model (DEM) to assess the stability of a critical pit wall where the multiple block failures were recorded at the bench and inter-ramp slope scale. The DFN-DEM approach adopted in this study could model the slope stability state using the shear strength reduction (SSR) method. According to the results of the simulations, the critical strength reduction factor (SRF) values derived from each numerical simulation were highly dependent on the DFN geometry configuration, and the trace length. To quantify the uncertainty associated with the assumptions established during the DFN-DEM modelling process, a series of models were simulated with different DFN configuration. At the inter-ramp slope scale, the simulations were predominantly unstable (SRF≤1.0) over 30 DFN realisations. The probability of failure (PoF) averaged 70% with a mean safety factor of 0.93 for the simulated DEM slope models while using the LE method, an average PoF of 40% and mean safety factor of 1.08 were estimated.

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