Reliable prediction of geotechnical risks in open pit mining

Abstract

The currently required minimization of geotechnical risks in open pit mineral mining includes timely prediction of slope failure probabilities and their impacts on personnel, environment, equipment, infrastructure and production efficiency of mines. The main tool to predict stability of pitwall slopes in modern geomechanics of rocks is the numerical modeling greatly dependent on the reliability of the source data. The risk prediction reliability is in focus of this study. It is preferable to use the notion “failure probability” as the criterion of pitwall stability as the uncertainty of parameters has already been determined quantitatively in this case. With the notion “stability factor” used as the stability criterion, it is required to add the calculated stability factor with the degree of variability of the initial parameters, with an emphasis on the reliability of geotechnical data. The reliability of the pitwall stability estimation largely depends on the geotechnical data reliability. The projects at the stage of a mineral field development should have the confidence level of data not lower than 80 %. The point rating system is presented for the estimate of the geotechnical data reliability. The procedure has been tested at some deposits at different project stages, and has proved to be handy, simple and objective. Using the described assessment system of the data reliability, the actual “standard” values of the stability factor are obtained for some open pit mines in operation and under design.