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Influence of the failure surface choice on the safety factor value during slope stability studies

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Category: Mining

Last Updated on 17 July 2018

Published on 03 July 2018

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Authors:

M.Fredj, Badji Mokhtar University, Annaba, Algeria,e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

A.Hafsaoui, Dr. Sc. (Tech.), Prof., Badji Mokhtar University, Annaba, Algeria,e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Y.Khadri, Dr. Sc. (Tech.), Badji Mokhtar University, Annaba, Algeria,e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

R.Boukarm, University Abderrahmane Mira, Bejaia, Algeria

Abstract:

Purpose. The aim of our work is to study the influence of the failure surface choice on the factor of safety for open-pit Phosphate mine case.

Methodology. To estimate the influence of failure surface, our study is focalized on the case of the real slope with complex geometry (Kef-Essnoun Mine), where an important sliding has happened. Firstly, the safety factor (FS) was calculated with Limit Equilibrium Method (LEM) and three non-circular potential surfaces were chosen. Secondly, calculation of the safety factor was performed through the Finite Difference Method (FDM). Finally, the different values of FS obtained for the failure surfaces were compared in order to find the closest approach to what happened in our study case.

Findings. The FDM is a useful tool for verification of LEM design due to precise calculation of the safety factor and a unique failure surface.

Originality. The originality of this work is to use two different approaches, LEM and numerical method (FDM), for analysing the slope stability design and the accuracy of this method in mining engineering field.

Practical value. This study illustrates that the results obtained by LEM in the cases (2) and (3) (FS 0.920 the minimum value) of failure surface are almost identical to those obtained using the FDM (FS 0.87), which reflects the reality of our case of study. On the other hand, in the case (1) LEM gives a contradictory result regarding that by FDM (FS 4.345), the sliding does not happen (total stability). The close agreement between the two analysis methods indicates that the FDM can be used as a practical and meaningful verification of conventional LEM of complex slopes.

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