Simulations of Seepage Flows in Dam Subjected to Varying Phretic Levels [ READ ]
Oladipupo S.OLADEJO and Umaru A.NDATSU
New Ede dam embankment is loosed and permeable and results from previous report established the possibility of erosion of fine particles from upstream to downstream of the dam embankment. Seepage problem was also suspected within the dam embankment due to the internal erosion. In this paper, seepage analysis of the earth dam was primarily conducted to evaluate the dam safety against the leakages through the embankment dam. Steady- state analysis, using SEEP2D was employed to investigate the seepage within the dam body at different water levels. As a particular boundary condition for analysis, the water level fluctuation was incorporated to simulate seasonal change and as a result; the various seepage phenomena were quantified such as flow rate, heads, hydraulic gradient, pore water pressure, velocity and seepage quantity. Correlation analysis was carried out to determine coefficients and significant levels; while regression equations were generated, using ANOVA to relate the dependent variable - water level with other seepage parameters (independent variables). The results of the simulated flow net showed ranges of seepage values of 8.1033 x 10-7 - 2.4396 x 10-7 m3/s/ unit width; for water levels at 19.6 m and 11.6 m respectively. At maximum and minimum phreatic levels of 19.6m and 11.6 m and full length of 877 m of dam axis, total seepage value were 7.11 x 10-4 m3/s (42 L/min) and 2.14 x 10-4 m3/s (13 L/min). There was high level of correlation between the seepage parameters (R > 0.99) and significant at < 0.05. The seepage quantities flowing through the dam suggested that the dam body was saturated regardless of water level. The result of this study showed that there is possibility of piping, internal erosion and excessive leakage through the dam.
Oladipupo S.OLADEJO and Umaru A.NDATSU
New Ede dam embankment is loosed and permeable and results from previous report established the possibility of erosion of fine particles from upstream to downstream of the dam embankment. Seepage problem was also suspected within the dam embankment due to the internal erosion. In this paper, seepage analysis of the earth dam was primarily conducted to evaluate the dam safety against the leakages through the embankment dam. Steady- state analysis, using SEEP2D was employed to investigate the seepage within the dam body at different water levels. As a particular boundary condition for analysis, the water level fluctuation was incorporated to simulate seasonal change and as a result; the various seepage phenomena were quantified such as flow rate, heads, hydraulic gradient, pore water pressure, velocity and seepage quantity. Correlation analysis was carried out to determine coefficients and significant levels; while regression equations were generated, using ANOVA to relate the dependent variable - water level with other seepage parameters (independent variables). The results of the simulated flow net showed ranges of seepage values of 8.1033 x 10-7 - 2.4396 x 10-7 m3/s/ unit width; for water levels at 19.6 m and 11.6 m respectively. At maximum and minimum phreatic levels of 19.6m and 11.6 m and full length of 877 m of dam axis, total seepage value were 7.11 x 10-4 m3/s (42 L/min) and 2.14 x 10-4 m3/s (13 L/min). There was high level of correlation between the seepage parameters (R > 0.99) and significant at < 0.05. The seepage quantities flowing through the dam suggested that the dam body was saturated regardless of water level. The result of this study showed that there is possibility of piping, internal erosion and excessive leakage through the dam.
