Slope Stability Analysis of the Gbeni Earth Dam (GB3) in Rutile - Sierra Leone
International Journal of Materials Science and Applications
Volume 9, Issue 6, November 2020, Pages: 66-70
Received: Jun. 21, 2020;
Accepted: Jul. 10, 2020;
Published: Dec. 16, 2020
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Simeon Stevenson Turay, Department of Civil Engineering, University of Sierra Leone, Freetown, Sierra Leone
Osman Koroma, Department of Civil Engineering, University of Sierra Leone, Freetown, Sierra Leone
Abdul Ahmed Koroma, Department of Civil Engineering, University of Sierra Leone, Freetown, Sierra Leone
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Earth slopes stability analysis is important in the design and construction of earth dams under different loading conditions. Several factors such as difference in water level or rapid drawdown in the reservoir, right after construction, and steady - state seepage may result in instability of Earth Dams for all possible combinations. In this study, three scenarios were evaluated for the Gbeni Earth Dam (GB3) at Sierra Rutile Mining Company in Sierra Leone. It is a zoned earth-filled embankment dam with respective upstream and downstream slopes of 1:3 and 1:2, having a horizontal sand blanket downstream. The upstream slope was subjected to both rapid drawdown in the reservoir of the earth dam and end of construction condition when there is no water present in the reservoir, whilst the downstream slope was assessed for steady seepage and end of construction conditions. The shape of the critical slip surface of both slopes was evaluated using a circular failure surface. The objective of this study was to assess the stability of these slopes under the above conditions using traditional analysis according to the theory of limit states and safety factor in GEO 5 software and its subprograms. The level of water on the upstream and downstream banks, the geotechnical properties of soil materials and boundary conditions of the dam were used as contribution variables and safety factors as the desired output. The study found out that the factor of safety against sliding of the upstream slope marginally drops within the short period after the start of rapid drawdown of water in the reservoir of the dam. Also, the downstream slope was found to be more stable under steady seepage. This accounts for the uncertainties involved in the strength of material, pore pressures in impervious clay core material, and long-term loading condition.
Rapid Drawdown, Steady – State Seepage, Limit States Equilibrium, Safety Factor, GEO 5 Software
To cite this article
Simeon Stevenson Turay,
Abdul Ahmed Koroma,
Slope Stability Analysis of the Gbeni Earth Dam (GB3) in Rutile - Sierra Leone, International Journal of Materials Science and Applications.
Vol. 9, No. 6,
2020, pp. 66-70.
Copyright © 2020 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/
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Bishop, A. W., & Bjerrum, L. (1960). The relevance of the triaxial test to the solution of stability problems. Proc. Research Conference Shear Strength of Cohesive Soils, (pp. 437-501).
Coduto, D. P. (1999). Geotechnical Engineering Principles and Practices. New Jersey: Alan Apt.
Craig, R. F. (2004). Craig’s Soil Mechanics (7th ed.). Spon Press.
Das, B. M. (2007). Advanced Soil Mechanics (Third ed.). Taylor & Francis.
Duncan, J. M. (1996). State of the Art: Limit equilibrium and finite element analysis of slopes. J. Geotech. Eng, ASCE, 122, 577-596.
Fattah, M. Y., Omran, H. A., & Hassan, M. A. (2015). Behavior of an Earth Dam during Rapid Drawdown of Water in Reservoir – Case Study. International Journal of Advanced Research, 110-122.
Fellenius, W. (1936). Calculation of the Stability of Earth Dams. Transactions, 2nd International Congress on Large Darns (pp. 445-459). Washington, DC: International Commission on Large Dams.
Khanna, R., Datta, M., & Ramana, G. V. (2014). End-of-construction stability of earth and rockfill dams. Proceedings of Indian Geotechnical Conference IGC-2014. Kakinada, India.
Paton, J., & Semple, N. G. (1961). Investigation of the stability of an earth dam subjected to rapid drawdown including details of pore pressure recorded during a controlled drawdown test. Pore pressure and suction in soils. 85-90.
Sherard, J. L., Woodward, R. J., Gizienski, S. F., & Clevenger, W. A. (1963). Earth and earth-rock dams. New York: John Wiley and Sons.
Stark, T. D., & Jafari, N. H. (2017). Rapid Drawdown Stability Analysis of San Luis Dam. 3rd North American Symposium on Landslides. Roanoke, Virginia, USA.
Terzaghi, K., & Peck, R. B. (1948). Soil Mechanics in engineering practice. New York: Wiley.