The quarries edges stability in opencast mines: a case study of the Jebel Onk phosphate mine, NE Algeria

The experience which accumulated over many years on problems of slope instability in quarries and opencast mines led to the development of several reliable methodologies for predicting discontinuities and selecting related consolidation works. Sloped bench faces that compose the overall slope in the studied case in this paper are evaluated from the stability prospective by applying a variety of stability analysis methods such as stereographic projection and software methods. The adopted approach is based on laboratory tests on understudied samples to designate the mechanical parameters and numerical modeling by implementing the finite element method. The latter, a vital tool to the quantitative determination of deformation mechanisms in large slope instabilities, is used to unravel the uncertainty of mechanical homogeneity properties of the involved materials at the level of discrete meshes in numerical computations that type of application proposes a procedural combination of an assortment of calculation stability methods through three steps. The first step is to quantify the alteration and fracturing conditions and to determine the mechanical parameters of Kef Essenoun rock mass by using slope mass rating (SMR) classification scheme, developed by Romana, to depict the strength of an individual rock slope. This system is based on the rock mass rating (RMR) geo-mechanical classification system of rocks, developed by Bieniawski, who refurbished that system with quantitative guidelines to get the rate of influence of adverse joint orientations. The second step is to uses the abacus method to estimate the stability of open-pit mines. The last step is to use a numerical modeling by applying Plaxis 8.2 calculation code.