Three-Dimensional Integral Modeling of Large Open-Pit Slopes: An Innovative Stability Analysis

The slope stability analyses in large-scale iron ore mining are usually conducted using two-dimensional models. Although this methodology helps to interpret the hydro-geomechanical behavior of open-pits, it might not capture the great complexity associated with mining environments. The geological formations associated to ore deposits may present complex spatial distribution of lithologies and ore grades as well as mechanical/hydraulic behaviors and properties. The distribution of lithologies and the ore grades are sufficiently well represented in the mining block model. However, the geotechnical model usually lacks reliable estimations of the properties and geologic structures due to the inherent complexity of this environment. Thus the block model appears as a potential vehicle for incorporating the geotechnical data and feeding some mechanical analysis routine to perform stability analysis in an integrated way. In this paper, we present some results of a FLAC3D model fully implemented using Python programming developed in the IPython console embedded in the FLAC3D 6.0 environment. The Numpy and Scipy libraries are used to fasten the calculations. The rock mass behavior is represented using the Mohr–Coulomb, generalized Hoek–Brown and Ubiquitous joints constitutive models according to the lithology. GSI is interpolated based on the borehole locations, and the properties of the intact rocks are considered homogeneous for each lithology. The attitude of the weakness planes considered in the ubiquitous model is attributed according to the structural domain discretization previously observed in the field. A case study of an iron ore mine of the state of Minas Gerais in Brazil is also presented. Some results of the stress–strain are presented. This promising tool is still under development to account for monitoring-based self-calibration.