Pit Slope Stability

Mining throughout the world has entered a new phase.  Larger mines, higher production rates and mining significantly below the water table have dramatically increased the importance of groundwater management.  Deposits once passed over due to groundwater concerns are now being brought into Read more... about The True Cost of Groundwater

Photo­grammetry is a remote data capture system that uses digital photo­grammetry to produce accurate 3­D structural models of mine features. Karl Llewelyn, a geotechnical engineer from SRK UK, explains how photogrammetric mapping can be used for pit slope angle optimisation. SRK was able to recommend an increase in the current pit slope angle configurations. In order to recommend these increased slope angles, it was highlighted to the client that pre-split blasting would need to be introduced to its mining practices. This would reduce the size of the zone of blast damage into the rock mass and decrease the likelihood of degradation of the bench faces, which stops the berms from filling with failure material and making them more effective to prevent rock falls. Read more... about Capturing Slope Data

With the variability of commodity prices and the constant increase of mining costs, it has become increasingly important to optimize pit slopes of mines, taking into consideration the complexity and the uncertainties presented by ground conditions. The variables in slope stability, geology, rock mass strength, structural defects, inherent and induced stresses, rock weathering, alterations, and groundwater, are well known, as are their impacts  on  slope  performance.  Most  variables  cannot  be  changed  to  optimize  slopes. However, groundwater is one variable that can be managed during pit excavation, to reduce the effect of pore pressure on slope stability. Hydrogeologists and rock mechanics engineers combine their efforts in order to quantify, simulate, and control the effect of groundwater pressures on pit slope performance. Based on comprehensive field hydrogeological data collection and interactive numerical groundwater and geotechnical modeling, it is possible to evaluate the water pore pressure effect on the pit slope, to provide an efficient depressurization strategy to meet the geotechnical engineering targets, and thus to develop cost-effective mine plans. This  paper  discusses  how  proper  management  of  groundwater  conditions  can contribute to mine planning and operations, through pit slope optimization. We show a complete approach from collection of hydrogeological data in the early stages of a project to design of an appropriate depressurization plan, taking into account the rock mass conditions, the mining plan, and the time to achieve an optimal pit slope. Read more... about Pit Slope Optimization Based on Hydrogeologic Inputs

This paper presents the second part of a study of the assessment of rock stress inputs on the performance of various new mining designs at the Ok Tedi large open pit mine in Papua New Guinea. Read more... about The Application of Rock Stress Inputs to Stability Assessments at Ok Tedi Mine, Papua New Guinea