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Hazard Management

To meet the global demand for copper to fuel the green-energy transformation, the mining industry is facing a step change where the next generation of block cave mines will see unprecedented footprint sizes and mining depths. Early experiences have already demonstrated that the rock mass and drawpoint responses encountered are complex and severe. These have exposed limitations in existing predictive tools, which have been developed based on observations involving lower stress environments and smaller draw column heights. This has resulted in greater risk related to geohazard management resulting in increasing safety hazards and costly interruptions to production.

To address these impacts, ICaRN is undertaking research to deliver more effective draw and support strategies to manage key hazards such as rockbursting and mudrush. The research projects initiated for these include objectives to improve identification, analysis of, and means to mitigate these geohazards to deliver value through reductions in damage or safety related delays, closed drawpoints, and support rehabilitation. Specifically, ICaRN’s research on rockbursting hazards have combined data analyses and machine learning with advanced numerical modelling to deliver new mechanistic-based, purpose-built tools for identifying zones susceptible to rockbursting, providing as output the potential depth of failure and failure mode (extensional or shear). ICaRN’s research on wet muck and mudrush hazards is taking a similar approach of integrating advanced data analyses and machine learning with mechanistic-based physical and numerical modelling. These are leveraging UBC expertise in debris flow hazard research, to better assess mudrush potential, trigger sensitivity, and corresponding travel path(s) and reach, to deliver to mining partner decision makers more robust hazard assessment and risk management tools.  

Figure: Logistic regression model showing spatial susceptibility to strainbursting damage for a block cave extraction level footprint
Figure: Application of the UBC Extensional/Shear Fracturing Criterion for brittle rock failure, applied to a block cave extraction-level footprint, showing the predicted depth of stress fracturing (spalling) for a given position of the undercut advance, and fit against measured data.
Figure: 3DEC-BBM modelling of pillar-scale spalling and support performance, comparing stress-induced brittle fracture damage and bulking for different support pressure scenarios at the end of the cave stress path simulated. The displacements corresponding to the undercut abutment stress and maximum pillar compression are included as fainter traces.

References

  • Rahjoo, M. & Eberhardt, E. (2021). Development of a 3-D confinement-dependent dilation model for brittle rocks; Part 1, derivation of a Cartesian plastic strain increments ratios approach for non-potential flow rules. International Journal of Rock Mechanics and Mining Sciences: In Press.
  • Rahjoo, M. & Eberhardt, E. (2021). Development of a 3-D confinement-dependent dilation model for brittle rocks; Part 2, formulation and parameterization based on the Cartesian plastic strain increments ratios approach. International Journal of Rock Mechanics and Mining Sciences: In Press.
  • Eberhardt, E., Lavoie, T. & Rahjoo, M. (2019). The importance of directional dilation in response to brittle rock failure for deformation-based support design in high stress environments. In Rock Mechanics for Natural Resources and Infrastructure Development; Proceedings of the 14th International Congress on Rock Mechanics and Rock Engineering, Foz do Iguaçu, Brazil, 13-18 September 2019. Edited by S.A.B. da Fontoura, R.J. Rocca & J.F.P. Mendoza. CRC Press, Boca Raton, pp. 2509-2516.
  • Gao, F., Kaiser, P.K., Stead, D., Eberhardt, E. & Elmo, D. (2019). Strainburst phenomena and numerical simulation of self-initiated brittle rock failure. International Journal of Rock Mechanics and Mining Sciences: 116, 52-63.
  • Gao, F., Kaiser, P.K., Stead, D., Eberhardt, E. & Elmo, D. (2019). Numerical simulation of strainbursts using a novel initiation method. Computers and Geotechnics: 106, 117-127.
  • Rahjoo, M. & Eberhardt, E. (2019). On the significance of recognizing the 3D directionality of fracturing under polyaxial stress states for understanding and modelling the 3D directional dilation of brittle rocks. In Rock Mechanics for Natural Resources and Infrastructure Development; Proceedings of the 14th International Congress on Rock Mechanics and Rock Engineering, Foz do Iguaçu, Brazil, 13-18 September 2019. Edited by S.A.B. da Fontoura, R.J. Rocca & J.F.P. Mendoza. CRC Press, Boca Raton, pp. 965-972.
  • Eberhardt, E., Diederichs, M.S. & Rahjoo, M. (2016). Pre-peak brittle fracture damage. In Rock Mechanics and Engineering, Volume 1: Principles. Edited by X-T. Feng. CRC Press/Balkema, Leiden, pp. 623-657.
  • Rahjoo, M., Woo, K-S. & Eberhardt, E. (2016). Stress-induced spalling analysis of extraction level pillars using a 3-D extensional strain failure criterion. In Proceedings, 50th US Rock Mechanics/Geomechanics Symposium, Houston, 26-29 June 2016. Paper 16-763, pp. 1-9.