Investigation of Bishop’s and Janbu’s Models Capabilities on Slope Stability Problems with Special Consideration to Open-Pit Mining Operations

One of the most effective parameters involved in the economics of open-pit mines is the pit slope angle so that a slope angle more than the optimum value increases the probability of a large failure in the pit wall, and a slope angle less than the optimum value leads to an increase in the stripping ratio and a reduction in the net present value of mine. In this work, considering the limit equilibrium methods of the modified Bishop, modified Janbu, and numerical models of the slope stability analysis, the effect of the overall slope angle on the economics of open-pit mines is investigated. In addition, it is shown that selecting an overall slope angle less than the optimum value leads to a reduction in the depth of open-pit mining (the ultimate pit depth), and consequently, a reduction in the net present value of mine. Finally, in the homogenous and isotropic media, the results of the Bishop, Janbu, and numerical modelings are close together.