The Large Open Pit Project

The Large Open Pit Project is an international research and technology transfer project on the stability of rock slopes in open pit mines. Planning for the project commenced early in 2004 when a scoping document outlining a draft research plan was submitted by CSIRO Australia (the Australian Commonwealth Scientific and Industrial Research Organisation) to a number of potential Sponsors for appraisal. An inaugural Project Sponsor's meeting was then held in Santiago, Chile, in August 2004, when the proposal was examined in detail by mining company representatives and a number of senior practitioners and consultants from across the open pit mining industry. Strong, positive responses to the proposal lead to the official commencement of the Project in April 2005. Ground stability and wall slope design are fundamental variables in the economics of operating large open pit mines. For the stakeholders, which includes the owners, mine management, the workforce and the regulators, the end goal is to achieve reliably engineered mine slopes that, if they do fail, do not cause loss of life, equipment damage, sustained losses of production, or the inability to achieve published reserves. Over the last ten to fifteen years these requirements have been hampered by critical gaps in our knowledge and understanding of the relationships between the strength and deformability of jointed rock masses and the likely mechanisms of failure. These shortcomings have been exposed by a number of spectacular slope failures that have resulted in multiple fatalities, production losses and unfavourable world-wide publicity. In turn, these undesirable events demonstrated a pressing need for innovative mining geomechanics research that stepped outside of the box and reassessed the fundamentals of rock mass strength and slope failure mechanisms from first principles. The challenge of stepping outside of the box and reassessing the fundamentals of rock mass strength and slope failure mechanisms from first principles was the driving force that created the LOP Project. The research plan developed for the project focussed on three elements: preparation and publication of an authoritative new generation pit slope Design Guidelines book that clearly outlined for today's practitioners what is the best approach to satisfy best practice at every stage of planning and operating an open pit mine; the effective use of geological and geotechnical data in assessing the strength and deformability of jointed rock masses and the likely mechanisms of slope failure; and hydrogeological studies to assess the effect of pore water pressures on the stability of closely jointed rock. The purpose of this keynote address is to outline the nature and impact of these three elements on the slope design process and how they are helping to expand the slope design practitioner's knowledge base and improve the reliability of rock slopes in large open pit mines.