Analysis by Numerical Simulation of the Geotechnical Behavior of Mining Slopes under the Influence of the Variations of the Geometric and Mechanical Parameters of the Bench Using RocScience (Slide Module Version 6.020): Case of an Open-Pit Mine
Better benches design enables to optimizes the risks of instabilities, to guarantee maximum of the ore recovery with minimum waste stripping. This requires detailed data on their geometric properties and the mechanical properties of the materials (soil and rock), thus defining the appropriate means for investigation, modeling and numerical calculations. The objective of this article is to study the geotechnical behavior of slopes and edges of a mining pit under the influence of variations in the geometric parameters of the bench and mechanical parameters of the ground in the case of open-pit mines. To do this, we used the stability calculation software well adapted to landslide problems, called RocScience (Slide module version 6.020). Four geometric models were tested in order to assess the slopes and the mining pit edges stability, in order to choose the best model for the application of the different parameter’s variation. The stability calculations showed the influence of variations in the geometric parameters of the benches and the mechanical parameters of the soil on the factor of safety. The results of variations in favor of a decrease in the bench height, slope angle and an increase in the bench width show an increase in the factor of safety and vice versa. With the first three models, under static conditions all the factors of safety are greater than or equal to 1.4, which shows a state of satisfactory long-term stability, whereas under Pseudo-static conditions, the factors of safety are all less than 1, which means that collapse is inevitable with these models. It can be seen that with a fourth model whose geometric characteristics, the factors of safety obtained are greater than 1.5 in static conditions and 1 in Pseudo-static conditions, which shows of the slopes and pit edges long-term stability. As for the variations in mechanical parameters, the factor of safety increases with the increase of the mechanical parameters in static and Pseudo-static conditions. The sandstone layer showed inevitable instabilities with values of the internal friction angle below 40？ and internal cohesion below 65 KPa. Instabilities are observed in the limestone layer with internal friction angle values below 35？ and internal cohesion below 120 KPa. The pegmatite showed a state of guaranteed stability in an interval of the internal friction angle ranging from 30？ to 35？ and internal cohesion ranging from 250 to 300 KPa outside which instabilities inevitably occur. The variation of the parameters showed a very low effect on the last two
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