Application of Numerical Modelling to predict Seismic Probability and Mitigate Associated Risks during the Craig Pillar Extraction at Morrison Mine, KGHM International.
A geomechanics study on how to safely extract the Craig Pillar at Morrison Mine without negatively impacting mine operations was initiated in mid-2013. Due to historical and future mining at Morrison, there was concern that elevated in situ stress magnitudes would be encountered during pillar extraction. A FLAC3D model was developed to simulate historical mining, and the model was qualitatively calibrated based on visual observations of stress induced rock mass damage. Once the model was adequately calibrated, forward projections of the pillar extraction were simulated to assess the potential for mine induced seismicity so that the associated risks, related to rock bursting and production difficulties, could be managed and mitigated. Areas of high risk where identified based on perceived probability of seismic activity and exposure of men and equipment to rock burst hazards. These high risks areas where targeted for dynamic support installation and comprehensive post-blast monitoring using the mine micro-seismic system and strategically located borehole extensometers. This presentation will overview the numerical model calibration process and demonstrate the model verification based on instrumentation data and visual observations of ground response to the actual pillar extraction.