Geomechanical Practices in Developing Open-Pit Slopes at Kinross Gold

ABSTRACT: Open-pit slope instabilities may lead to personnel injuries and/or equipment damages in some cases. However, in most cases, these events require mitigation measures like step-outs, unloading, buttressing and local slope flattening with potential impact on mine production in short or long term. Noncompliance with slope design criteria, which may be a contributing factor in slope instability, potentially creates an unsafe working environment and has a negative impact on mine performance. Achieving an optimized balance between open-pit slope performance and financial objectives is the goal of many corporate risk management systems in the mining industry. The basis for a practical and achievable slope design is a reliable geomechanical model. Application of this model and slope design acceptance criteria leads to selection of slope design parameters that derive from various geomechanical analyses and numerical modeling, and this process reflects the risk tolerance level of the project or operation owner. In the mine production stage, i.e., implementation of the slope design, operational controls in drilling and blasting, bench face cleaning and visual and instrumentation monitoring play a key role in achieving the recommended slope design. Building the geomechanical model and subsequent slope design normally start with data collection by launching a drilling and testing program with or without outcrop or exposed bench mapping. As mining progresses, the initial slope design is updated based on actual slope performance and data collected through ongoing programs, for instance, physical and image mapping. Hydrogeological input to slope stability analysis is critical in many cases particularly in weak rock masses. Input data normally come from non-mining functional groups in early stages of a project or mine operation. This practice may create slope performance issues in the design implementation phase. This presentation discusses topics described above with examples from Kinross mines. The intention is to draw discussions from peers, initiate ideas in research and development, and help practitioners learn from industry cases.