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IJSTR >> Volume 8 - Issue 4, April 2019 Edition

International Journal of Scientific & Technology Research  
International Journal of Scientific & Technology Research

Website: http://www.ijstr.org

ISSN 2277-8616

Slope Stability Of The Middle Stack Of An Open Pit

[Full Text]



Wang Yiming, Trevor Siame, Victor Mwango Bowa



Slope failure; middle stack; the factor of safety; the probability of failure; drained and undrained conditions; acceptance failure criteria.



Chimiwungo main open pit has experienced slope failure in the weathered rock formation in the middle stack for a decade now. In this article, the geotechnical analysis was conducted to determine the factor of safety and probability of failure of the middle stack using limit equilibrium method under both drained and undrained conditions. The factor of safety and probability of failure index were calculated as they provide the objective measure of the risk of the failure associated with a slope design. The actual stack performance was compared to various slope stability acceptance criteria with results subjected to a more thorough analysis of the consequences of failure. The study indicates that under dry to semi-drained conditions, the factor of safety and the probability of failure were compliant to all the acceptability slope stability failure criterion. This entails under dry and partially drained conditions, the middle stack of the Chimiwungo Open Pit is predicted to remain stable. As the undrained condition of the stack is above 30% of water content, the resulting safety factor and the probability of failure becomes out of compliance with the acceptance slope stability failure criterion. This entails the performance of the stack with respect to acceptance failure criteria falls below the minimum mean factor of safety and violates probability acceptance failure criteria, leading to unstable stack. The study recommends major modification to the stack geometry and that the stability of the stack be tested in both drained and undrained conditions prior to implementations.



[1]. Terzaghi, K. (1963). Stability of steep slopes on hard, unweathered rock. Géotechnique, London, 12(4), 251-270.
[2]. Kovari, K. and Fritz, P. (1975). Stability analysis of rock slopes for plane and wedge failure with aid of a programmable pocket calculator. 16th US Rock Mechanics. Symposium, Minneapolis, USA, 25 – 33.
[3]. Cavers, D.S. (1981). Simple methods to analyse buckling of rock slope. Rock Mechanics, 14(1), 87-104.
[4]. Goodman, R.E. (1989). Introduction to rock mechanics, 2nd ed., Wiley, New York.
[5]. Anbalagan, R. (1992). Landslide hazard evaluation and zonation mapping in mountainous terrain. Eng. Geol. 32, 269–277.
[6]. Sharma, S., Raghuvanshi, T., and Anbalagan, R. (1995). Plane failure analysis of rock slopes. Geotechnical and Geological Engineering, 13(1), 105–111.
[7]. Nawari, O., Hartmann, R., and Lackner, R. (1997). Stability analysis of the rock slopes with the direct sliding blocks method. International Journal of Rock Mechanics and Mining Sciences, 34(3):220–235.
[8]. Bobet, A. (1999). Analytical Solutions for Toppling Failure. International Journal of Rock Mechanics & Mining Sciences, 36(7), 971 – 981.
[9]. Goodman, R.E. and Kieffer, S.D. (2000). Behaviour of rock in slopes. Journal of
Geotechnical and Geoenvironmental Engineering. Vol. 126, No. 8, pp 675 – 684.
[10]. Shukla, S.K., Khandelwal, S., Verma, V.N., Sivakugan, N. (2009). Effect of surcharge on the stability of anchored rock slope with water filled tension crack under seismic loading condition. Geotechnical and Geological Engineering, 7 (4), 529–538.
[11]. Hossain, M.M. (2011) Stability analysis of anchored rock slopes against plane failure subjected to surcharge and seismic loads. Retrieved from http://ro.ecu.edu.au/ theses/139 on December 18’ 2018.
[12]. Tang, H., Yong, R., Ez Eldin, M.A.M. (2016). Stability analysis of stratified rock slopes with spatially variable strength parameters: the case of Qianjiangping landslide. Bulletin of Engineering Geology and the Environment.
[13]. Chen, C.S., Xia, Y.Y., Bowa, V.M. (2017). Slope stability analysis by polar slice method in rotational failure mechanism. Computers and Geotechnics, 81:188–94.
[14]. Bowa, V.M., and Xia, Y. (2018a). Influence of Counter-Tilted Failure Surface Angle on the Stability of Rock Slopes Subjected to Block Toppling Failure Mechanisms. Bulletin of Engineering Geology and the Environment, 77(4):120-140.
[15]. Stead, D., Eberhardt, E., Coggan, J.S. (2006). Developments in the characterization of complex rock slope deformation and failure using numerical modelling techniques. Engineering Geology, 83, 217–235.
[16]. Mohtarami, E., Jafari, A., and Amini, M. (2014). Stability Analysis of Slopes against Combined Circular–Toppling Failure. International Journal of Rock Mechanics and Mining Sciences, 67(1):43-56.
[17]. Bowa, V.M., and Xia, Y. (2018b). Stability Analyses of Jointed Rock Slopes with Counter-titled Failure Surface subjected to Block Toppling Failure Mechanisms. Arabian Journal for Science, Research Article: Civil Engineering, 43(10):5315-5331.
[18]. Yang, X.L., and Zou, J.F. (2006). Stability factor for rock slopes subjected to pore water pressure based on the Hoek-Brown failure criterion. International Journal of Rock Mechanics& Mining Sciences, 43(7), 1146-1152.
[19]. Shukla, S.K. and Hossain, M. M. (2011). Stability analysis of multi – directional anchored rock slope subjected to surcharge and seismic loads. Soil Dynamics and Earthquake Engineering.
[20]. Kulatilake, P.H.S.W., Wang, L., Tang, H., and Liang, Y. (2011). Evaluation of rock slope stability for Yujian River dam site by kinematic and block theory analyses. Computers and Geotechnics, 38(1), 846–860.
[21]. Ermias, B., Raghuvanshi, T.K., Abebe, B. (2017). Landslide Hazard Zonation (LHZ) around Alemketema Town, North Showa Zone, and Central Ethiopia - A GIS based expert evaluation approach. Int. Jr. Earth Sci. & Engg. 10 (1), 33–44.
[22]. Yan, M.J., Xia, Y.Y., Liu, T. Bowa, V.M. (2019). Limit Analyses under seismic conditions of a slope reinforced with prestressed anchor cables. Computers and Geotechnics, 108, 226-233.
[23]. Bowa, V.M., and Xia, Y. (2018c). Modified Analytical Technique for Block Toppling Failure of Rock Slopes with Counter-Tilted Failure Surface. Indian Geotechnical Journal, 48(4):713-727.
[24]. Bowa, V.M., Xia, Y., Yan, M., and Kabwe, E. (2019). Toppling of the Jointed Rock Slope with Counter-tilted Weak Plane Planes Influenced by the response to Local Earthquake. International Journal of Mining and Mineral Engineering, 120(4):60-78.
[25]. Priest, S.D., and Brown, E.T. (1982). Probabilistic stability analysis of variable rock slopes. (Transactions of Institution of Mining and Metallurgy, Section A, 1983. Mining Industry, Pp, 92.
[26]. Terbrugge, P. J. (2011). Slope Stability acceptability Criterion, SRK House, 265 Oxford Road, Illovo 2196, P.O. Box 55291, Northlands, 2116, Republic of South Africa.
[27]. Read, J., and Stacey, P.F. (, 2009). Guidelines for Open Pit Design, CSIRO Publishing, Melbourne, 2. ROCSCIENCE, SWEDGE – Program for evaluating the geometry and stability of surface wedges in rock slopes. ROCSCIENCE Inc., Toronto.
[28]. ROCSCIENCE Inc. (2002) Slide User’s Guide, Version 5.0 ROCSCIENCE Inc., Toronto, Ontario (Canada).
[29]. Sjöberg, J. (1999). Analysis of large scale rock slopes. Doctoral thesis, Division of Rock mechanics, Lulea University of Technolog