The end goal in open pit mining is to achieve reliable mine slopes that, if they fail, do not cause loss of life, equipment damage, sustained losses of production, or the inability to achieve published reserves. Over the 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, with divided opinions on how to characterise the rock mass. Commonly, there has been an uncritical derivation of physical rock properties from empirical classification systems and an equally uncritical use of such physical properties in design analyses without a clear understanding of the geological framework. These inadequacies have been exposed by a number of spectacular large open pit slope failures, resulting in multiple fatalities, production losses, and unfavourable worldwide publicity. Collectively, they have demonstrated a need to step outside the box and reassess the fundamentals of rock mass strength and slope failure mechanisms from first principles.
The LOP Project slope design research tasks have been and continue to be directed at addressing these inadequacies by enabling the effective use of geological and geotechnical data in assessing rock mass characteristics, 3D modelling, and simulation of slope failure mechanisms, design analysis, and uncertainty analysis. The research tasks performed by the LOP project since 2009 have been drawn on the experience of the sponsors and a number of industry consultants and practitioners who have shared their knowledge and experience by contributing to several of the sections in the LOP Guidelines and Research Projects below.
LOP Completed Projects
Objectives: The potential effects of earthquakes on the stability of open pit mines were addressed in this research work, also incorporated in Chapter 10 of the design guidelines book. The outcome of this study concluded that: Topographic effects are important reasons why pit slopes are more stable than natural slopes. [Read more]
Objectives: All rock masses are subjected to in situ stresses resulting from the weight of the overlying strata and from locked in stresses of tectonic origin. The excavation of an open pit results in disruption of the existing stress field with some of the stresses being relieved, while others [Read more]
Provider: ITASCA Objectives: The objective of this research work was to establish a numerical modeling approach to compute the distribution of water pressures in a pit slope in low permeability fractured rocks, and the response of water pressure with time to mining. The failure of a slope necessitates one [Read more]
Provider: ITASCA Objectives: The main focus of early years of the original LOP Project (2005 to 2014) was on preparation of the book Guidelines for Open Pit Slope Design and delivery of research tasks that included Siromodel (also known as the OPS or Open Pit Simulator software), JointStats, Stepsim4, and the development [Read more]
LOP II Completed Projects
Provider: Itasca Consulting GroupObjectives:Open pit excavation results in disruption of the in-situ stress field with some stresses being relieved and others being increased. Damage to the rock mass behind open pit walls results from this stress redistribution and blasting practices. Damage to the rock mass from both causes has important [Read more]
LOP II On-going Projects
Objectives:Although most mining companies have in-house systems in place for slope monitoring, experience indicates that mining operations continue to be surprised by the occurrence of negative geotechnical events. Site engineers want and need help in the selection and design of [Read more]
Provider: Piteau Associates UK LimitedObjectives:Understanding groundwater flow, pore pressures and effective stress in pit slopes is vital for the delivery of economic and safe slope designs. Pore pressure is one variable controlling slope stability which can be measured, simulated, predicted [Read more]
Provider: Geoapp s.r.l. Objectives: Nowadays most large open pit mines have sophisticated systems in place for near real-time slope monitoring. Despite the availability of massive datasets of monitoring data, negative events associated with slope failures, having in some cases [Read more]