FINITE ELEMENT METHOD OF SEEPAGE AND STABILITY ANALYSIS OF SAURA-KEFFI EARTH DAM
Keywords:Finite element Method, SCM (Seepage Control Measures), SEEP/W, SLOPE/W, GEOSTUDIO Software
Finite element method (FEM) based analysis using the SEEP/W and SLOPE/W sub-programme options of a GEOSTUDIO software was used to analyze Saura-Keffi earth dam in Nasarawa State, Nigeria with the view to analyze the dam seepage and its stability. The created dam geometry was assigned material properties and boundary conditions at reservoir water levels of: minimum (3 m), normal (6 m) and maximum (7 m). The analysis was conducted under the cases that the dam was without and with seepage measures (SCM). The results of the analyzed semi-permeable homogenous dam revealed a percentage reduction inseepage flux to 28.3% when the dam was considered with a central core and complete cut-off trench along the dam crest axis. see figure 7. The pore-water (PWP) revealed a decrease in value from (12 to 11.2) kPa at minimum water head with SCM. The PWP further increased by 18.9% as water rises from 6 m to 7m with SCM. The exit gradient showed an insignificant increase in value of 1.2% with the construction of SCM which indicates less flow at the exit end of the dam leading to increase in stability. The horizontal filter drain at the downstream lower and kept the phreatic line within the dam body to allow for adequate embankment and foundation drainage as shown in figure (5&6). The F.S at the maximum water level revealed an increase in value from 1.27 to 1.52 when a horizontal filter was considered. The Morgenstern-priced method of slope stability was used to estimate an acceptable minimum F.S of 1.52 at 0.5 lambda value with the introduction of horizontal filter.
Ahmed, S., Batagarawa, R. L., and Etim,C. 2022. Environmental Impact Assessment of the Proposed Earth Dam at Nigerian Defence Academy (NDA) Permanent Site. Journal Of Science Technology and Education 10(2): 133, ISSN 2277-0011; www.atbuftejoste.com.
Terzaghi, 1929. AASHTO A-2-4. Soil Classification for Granular Materials (35% or less passing No. 200 sieve). Developed by America Association of State & Transportation officials, retrieved at http://www.aboutcivil.org. Retrieved date: Aug 20th, 2022
Terzaghi, 1929. AASHTO A-2-6. Soil Classification for Silty Clay Materials (>35% passing No. 200 sieve), developed by America Association of State & Transportation officials.
BS 882 1983: Part 2. Specification for Aggregate from natural Sources for Concrete. Pp. (3) published by British Standard Institution
BS 882 1990: Part 2. Specification for Aggregate from natural Sources for Concrete. Pp. (4) published by British Standard Institution. http://www.aboutcivil.org.
Fernando,S., Luiz, F.S.,and Bruno,S. (2020). Guidelines and recommendations on minimum factors of safety for slope stability of tailings dams. Soils and Rock an International journal for Geotechnical and Geoenvironmental Engineering,43(3): 378 – 384
GEO-SLOPE International Ltd, (2004-2021). Stability Modeling with GeoStudio. 1200, 700 - 6th Ave SW, Calgary, AB, Canada T2P 0T8: (5 – 10). www.geo-slope.com. Retrieved date: September 15th, 2021:
Haseeb, J. 2017. Phreatic line and Horizontal Drain in Earth fill Dam.About civil.com, retrieved at www.aboutcivil.org Retrieved date: Aug 26th, 2022
Kamanbedast, A. 2012. Analysis of Earth Dam: Seepage and Stability using Ansys and Geo-Studio Software. Sciences Journal 17 (9): 1087-1094.
Labban, A.L. (2018). Seepage and Stability Analysis of the Earth Dams under Drawdown Conditions by using the Finite Element Method. Electronic Theses and Dissertations. University of Central Florida Orlando, Florida. “STARS” www.stars.library.ucf.edu/etd/6157. Retrieved date February 24th, 2021.
Mishal UR and Khayyun TS. (2018). Analysis of an Earth Dam Using GEO-SLOPE model under different Soil Conditions. Engineering and Technology Journal 36(5) : 523, Part A
Morgenstern, N.R., and Price, V.E. 1965.The Analysis of the stability of general Slip surfaces. Geotechnics 15(1): 79-93. Retrieved at Online Help /Geo5/. www.finesoftware.eu. Retrieved date: August 28th 2022
Nada, M.A and Maysam T.A. 2020. Seepage and Slope Stability Analysis for Hemrin Earth Dam in Iraq using Geo-studio Software. Solid State Technology.63(3): 3434-3448.
Salama, N.2018. Seepage and Stability Analysis of Earth Dams under Drawdown Conditions using Finite Element Method. Electronic theses and Dissertations, 2004-2019. 6157. “STARS” University of Central Florida, USA.
Shivakumar, S. 2015. Seepage and Stability Analyses of Earth Dam Using Finite Element Method. ICWRCOE 2015, Elsevier B.V. Aquatic Procedia 4 ( 2015 ) pp.(876 – 883) . India.
Wikipedia. 2022 Slope Stability analysis. Retrieved at http://www.en.m.wikipedia.org Retrieved date: Aug 28th, 2022
Zedan, A.J. 2017. Seepage Analysis through an Earth Dam (KHASA-CHAI Dam) as a Case Study. Engineering and Technology Journal Vol. 35(2): 174. Part A.