Seepage and Slope Stability Analysis of Earthen Dam: A Case Study of Koga Dam, Ethiopia

• Authors: Amanuel Zewdu
• Languages of publication: EN

Abstracts

EN

Evaluations of an earth-fill dam throughout its service life must ensure the stability of it against seepage and slope failure. This study presents the seepage and slope stability of the Koga earth-fill dam. The analyses were carried out using a finite element based PLAXIS 2D software, and covers the whole dam body; including 20 m of foundation depth. The behavior of both the body and the foundation of the dam were described using the Mohr-Coulomb criterion. Assessments of safety factor and quantity of seepage through the main body of the dam and foundation were carried out at different critical loading conditions. In this study, seepage analysis was undertaken of flow rate, pore water distribution and location of phreatic line. Additional actual field data measurements and observatory investigation were also carried out. From the simulated results, the average flow rate of seepage for the entire length of the body of the dam at normal pool level was equal to 0.06085 m3/s, whereas the figure for that through the foundation of the dam was 0.01937 m3/s. Moreover, total seepage through the main body of the dam at the current reservoir level was 0.04982 m3/s, while the actually measured quantity of seepage accumulated at the downstream toe of the dam was 0.04644 m3/s. The simulated and measured seepage discharges are 93.2 % similar. Based on the result of this study, the resulting factor of safety values during end of construction, steady state condition and rapid drawdown condition were 1.6221, 1.6136 and 1.2199, respectively. Using recommended design standards: United States army corps of engineers (USACE), British dam society (BDS) and Canadian dam association (CDA), the slope stability analysis of the Koga earth dam at all critical loading conditions are safe.

Keywords

EN

Finite element method; PLAXIS 2D; Seepage; Stability analysis

Discipline

• GEOPHYSICS: GEOPHYSICS

• Publisher: Scientific Publishing House „DARWIN”
• Journal: World News of Natural Sciences
• Year: 2019
• Volume: 26
• Pages: 191-217

Contributors

author

Amanuel Zewdu

• Department of Hydraulic and Water Resourcing Engineering, Debre Tabor University, Debre Tabor, Ethiopia

References

• [1] Pelecanos, L., S. Kontoe, and L. Zdravković. Dam-reservoir interaction effects on the elastic dynamic response of concrete and earth dams. Soil Dynamics and Earthquake Engineering 82 (2016) 138-141
• [2] Sherard, J. L., & Dunnigan, L. P. (1989). Critical filters for impervious soils. Journal of Geotechnical Engineering, 115(7), 927-947.
• [3] Pandey, R., Mittal, S. K., & Choudhary, M. K. (2016). Flow characteristics of sharp crested rectangular weir: a review. Inernational Journal of Innovation, Science, Engneering and Technology, 3, 171-178.
• [4] Suh, Jangwon, Yosoon Choi, Tae-Dal Roh, Hyi-Jun Lee, and Hyeong-Dong Park. National-scale assessment of landslide susceptibility to rank the vulnerability to failure of rock-cut slopes along expressways in Korea. Environmental Earth Sciences 63, no. 3 (2011) 619-632.
• [5] Hsu, Y. C., Lin, J. S., & Kuo, J. T. (2007). Projection method for validating reliability analysis of soil slopes. Journal of geotechnical and geoenvironmental engineering, 133(6), 753-756.
• [6] Khalid, S., Singh, B., Nayak, G. C., & Jain, O. P. (1990). Nonlinear analysis of concrete face rockfill dam. Journal of geotechnical engineering, 116(5), 822-837.
• [7] Omofunmi, O. E., Kolo, J. G., Oladipo, A. S., Diabana, P. D., & Ojo, A. S. (2017). A review on effects and control of seepage through earth-fill dam. Current Journal of Applied Science and Technology, 1-11.
• [8] Xu, Y., & Zhang, L. M. (2009). Breaching parameters for earth and rockfill dams. Journal of Geotechnical and Geoenvironmental Engineering, 135(12), 1957-1970.
• [9] Foster, M., Fell, R., & Spannagle, M. (2000). The statistics of embankment dam failures and accidents. Canadian Geotechnical Journal, 37(5), 1000-1024.
• [10] Xu, Y., & Zhang, L. M. (2009). Breaching parameters for earth and rockfill dams. Journal of Geotechnical and Geoenvironmental Engineering, 135(12), 1957-1970.
• [11] Cheng, Y. M., Lansivaara, T., & Wei, W. B. (2007). Two-dimensional slope stability analysis by limit equilibrium and strength reduction methods. Computers and Geotechnics, 34(3), 137-150.
• [12] Shivamanth, A., Athani, S. S., Desai, M. K., & Dodagoudar, G. R. (2015). Stability Analysis of Dyke Using Limit Equilibrium and Finite Element Methods. Aquatic Procedia, 4, 884-891.
• [13] Galavi, V., Petalas, A., & Brinkgreve, R. B. J. (2013). Finite element modelling of seismic liquefaction in soils. Geotechnical Engineering Journal of the SEAGS & AGSSEA, 44 (3), 2013.
• [14] Rientjes, T. H. M., Haile, A. T., Kebede, E., Mannaerts, C. M. M., Habib, E., & Steenhuis, T. S. (2011). Changes in land cover, rainfall and stream flow in Upper Gilgel Abbay catchment, Blue Nile basin–Ethiopia. Hydrology and Earth System Sciences, 15(6), 1979-1989.
• [15] Yohannes, H., & Soromessa, T. (2018). Land suitability assessment for major crops by using GIS-based multi-criteria approach in Andit Tid watershed, Ethiopia. Cogent Food & Agriculture, 4(1), 1470481.
• [16] Tan, S. A., Tjahyono, S., & Oo, K. K. (2008). Simplified plane-strain modeling of stone-column reinforced ground. Journal of Geotechnical and Geoenvironmental Engineering, 134(2), 185-194.
• [17] Zardari, M. A., Mattsson, H., Knutsson, S., Khalid, M. S., Ask, M. V., & Lund, B. (2017). Numerical analyses of earthquake induced liquefaction and deformation behaviour of an upstream tailings dam. Advances in Materials Science and Engineering, Volume 2017, Article ID 5389308, 12 pages. https://doi.org/10.1155/2017/5389308
• [18] Hasani, H., Mamizadeh, J., & Karimi, H. (2013). Stability of slope and seepage analysis in earth fills dams using numerical models (Case Study: Ilam Dam-Iran). World Applied Sciences Journal, 21(9), 1398-1402.

• Document Type: article