Geomechanical risk in mining is universally understood to depend on many apparently disparate factors acting together such as stress, stiffness, mine geometry, rock mass character, rock type, structure, excavation rate and volume, blasting, and seismicity. We have worked on many case studies over the years in both underground and open pit mines with the objective of discovering and documenting the correlation of such factors with the experience of geomechanical failure. Whether that failure is slope failure, strainbursting, fault slip-induced rockbursting, roof fall, or any other of many possible failure types, statistical correlations among the different classes of data can be found, and predictive rules for understanding geohazard based on their quantitative combination can be established and deployed in day-to-day operations. This data-driven approach requires application of methods and avoidance of pitfalls that can be standardised into a universally applicable workflow. We discuss the workflow and the pitfalls in analysis to be avoided through case study examples.
The development of the geotechnical risk model for the Chuquicamata mine started in 2005 and included the safety and economic impacts of slope failures at different scales (Tapia et al. 2007; Steffen et al. 2008). The model has been updated recently to include a quantitative evaluation of large economic impacts derived from inter-ramp and overall slope failures using a probabilistic approach (Contreras 2015). This paper describes how the later component of the model was used as a tool for the evaluation of four closure alternatives for the open pit. The methodology included three main tasks: 2. Evaluation of the consequences of slope failure associated with economic losses derived from impacts on production and costs. 3. Generation of risk maps to compare several closure alternatives. The results of these analyses provided information on magnitude of impacts and their likelihood for the four closure alternatives evaluated. The evaluation of these results facilitated the selection of the appropriate closure alternative considering the mine reference criteria for economic risk.