This new ACG conference seeks to provide a forum for mining geomechanical practitioners around the world to improve on assessing, quantifying, communicating and managing mining geomechanical risk to maximise shareholder value.
- Assessing and quantifying uncertainty and variability.
- The risk and opportunity value of information.
- Qualitative and quantitative assessment of mining geotechnical risk.
- Safety, economic and environmental geotechnical risk acceptance levels.
- Communicating geotechnical risk to different stakeholders.
- Management of mining geotechnical risk.
- Risk assessment and risk-based design.
- Integration of geotechnical risk in mine planning and mine design processes.
This conference targets all geomechanics practitioners, consultants, researchers and mining engineers from all geomechanics disciplines in mining as well as senior executives faced with managing the business risks. The conference will address risk from geotechnical fields in mining including surface and underground rock mechanics, tailings and backfill, environmental geomechanics and mine closure.
Dr Johan Wesseloo
Senior Research Fellow — Rock Engineering
Project Leader — mXrap Development
Australian Centre for Geomechanics
Johan has been involved in geotechnical engineering since 1998, with experience in both underground and open pit environments. Johan obtained a BEng (Civil), MEng and PhD (Geotechnical) from The University of Pretoria, South Africa and is Fellow of the Southern African Institute of Mining and Metallurgy. He started his career as a geotechnical engineer with SRK Consulting, South Africa. In 2007, Johan joined the Australian Centre for Geomechanics, where he led and completed the ACG’s High Resolution Seismic Monitoring in Open Pit Mines project and the Mine Seismicity and Rockburst Risk Management. Johan has an interest in the rock engineering aspects of mine-induced seismicity and developed several procedures and methods for seismic analysis for rock engineering purposes and mining seismic hazard assessment methods, which are integrated into mXrap Apps.
Professor John Hadjigeorgiou
University of Toronto, Canada
Professor Hadjigeorgiou holds the Pierre Lassonde Chair in Mining Engineering at the University of Toronto. John previously served as head of the Department of Mining, Metallurgical and Materials Engineering at Université Laval in Quebec City.
Dr Hadjigeorgiou is a PEng with over 25 years of international experience in mining engineering. John is a past recipient of the John Franklin Award from the Canadian Geotechnical Society and the Rock Mechanics Award from the Canadian Institute of Mining. John is a fellow of the Canadian Institute of Mining and Metallurgy and holds the ICD.D designation from the Institute of Corporate Directors.
Dr John Lupo
Newmont Asia Pacific, USA
Dr Lupo holds a PhD in geotechnical engineering. He has over 30 years’ experience working within the mining industry. He currently is the Senior Director of Geotechnical and Hydrology at Newmont Mining Corporation in Denver, Colorado, USA.
Keynote address: Geotechnical risk-informed decision making in mining
Barrick Gold of North America, USA
Bob has over 35 years consulting and industry experience in mining geomechanics, following a short career as a welder-mechanic. He has degrees in geology and geological engineering from the University of Utah. His experience includes association with several Utah and Colorado based consulting firms in the 1980s, working on projects primarily in the open pit and underground coal mining sector in the Western US, Canada and Indonesia. This early experience included a period as manager of a rock mechanics laboratory.
Bob joined Barrick in 1988 as senior geotechnical engineer for Goldstrike Mines in Nevada, and evolved into global projects and operations support. He joined Newmont’s Global Geotechnical Group in 2012 as a senior director, and returned to Barrick in 2014. In his current position, Bob leads a global corporate technical team, with responsibilities that span geotechnical design and performance for Barrick’s open pit and underground mining operations, tailings and heap leach facilities, and water management structures.
Keynote address: Experience-based design and development of excavated slopes
The mining geomechanics community has developed a variety of approaches applied to the design of excavations in rock that are particularly deterministic or probabilistic, or a combination of both. In the author’s opinion, a risk based approach to slope design for large open pit excavations should be done only where relevant practical experience can be applied, potential failure modes are well understood; and designs are founded on an adequate geological model that includes a highly reliable assessment of small and large scale structural weakness. An approach to risk, or in this case, experience based slope design, should take advantage of a good understanding of potential geological controls. The author will draw upon relevant experience to show how a combination of deterministic and risk based analysis can be used to design slopes that: maximize economy (minimize waste rock stripping requirements); take advantage of design flexibility where potential for instability is recognized from the geological model, and; how to account for the influence of ground and surface water. To do the job correctly requires a high level of collaboration and an interactive design approach with the slope engineer, mine planner, operations, and others stakeholders as local conditions dictate.
As for performance of the experience based designs, mine operators typically adopt an observational approach towards continuing development of excavated slopes that are in some state of motion that varies from elastic to plastic. This would also apply to underground operations where mine development influences the stability of adjacent slopes, or the crown pillar. Operators feel comfortable about doing this, based to some degree on relevant experience, the instruments they use to monitor movement, measures in place to manage risk potential and the skill-sets of individuals charged with the design and management of the system, or process. Decisions regarding acceptance of the design and development approach are typically based on an assessment of the consequences in the event that failure occurs that range from the bench to inter-ramp scale; and what contingencies are available to safely manage instability and achieve production targets. The risk assessments have been done and approved by all key stakeholders. Mining may continue until reaching a movement rate threshold that is defined in their trigger action response plan (TARP). Success or failure depends on how well all of the parts of the design and management process work. Failure of only one of many risk mitigating critical controls could lead to an emergency level event.
In support of the experience based design and development approach summarized above, further discussion will explore the strengths and weaknesses of excavated slope designs that are typical in the mining industry and likely to persist; even as mines become increasingly automated and un-manned. In particular, the influence of large and small scale structural weakness that can impact slope performance and the influence of groundwater on slope stability are often underestimated. Results of risk assessments are often deficient for purpose due to bias in risk ranking and lack of site-based knowledge needed for developing a sufficiently reliable level of qualification, or quantification. Performance monitoring instrumentation is often deficient enough such that potentially dangerous conditions can develop before the mine operator has time to mitigate a developing problem. Fortunately, instrumentation is increasingly improving for monitoring performance with the ability to detect changes with a high level of precision, data validation using redundant systems, and transmission of data in near real-time, so that informed decisions and communication with all stakeholders can be quickly made. Capabilities of instrumentation that are fairly new to the mining industry and currently in development are well known to the interested and informed slope engineer; but importantly, limitations are often underestimated and need to be equally well, or perhaps even better understood than the capabilities. Designing and deploying integrated performance monitoring systems that will help the engineer and mine operator to detect, capture, report and act quickly and appropriately on anomalous ground movement can be difficult to sell to mine management, until such a time that an emergency motivates approval.
Professor Dirk Van Zyl
University of British Columbia, Canada
Dirk has more than 30 years’ experience in research, teaching and consulting in tailings and mined earth structures. During that period he was a faculty member for 13 years at four universities in the US and Canada. For the last 10 years, much of his attention has been focussed on mining and sustainable development. He has been involved internationally in many mining projects. These projects covered the whole mining lifecycle; from exploration to closure and post-closure, in a large range of climatic and geographic environments. Dirk’s present research is in the area of the contributions that mining makes to sustainable development as well as the application of life cycle assessment to mined earth structures.