Effect of Homogeneous Earth Dam Hydraulic Conductivity Ratio (Kx/Ky) with Horizontal Drain on Seepage

Focus of this research is to study and compare the efficacy of the use of horizontal drains in reducing the adverse effects of seepage at an assumed homogeneous earth dam. For this purpose, 78 different numerical models were simulated using Seep/w software, based on finite elements. Design variables include dam slopes, horizontal drain length and ratio of horizontal hydraulic conductivity to vertical hydraulic conductivity. Also results from numerical simulation, was compared with three other researchers. Representative graphs have been plotted for horizontal drains, are nonlinear and covering all the practical ranges of the dam geometry. Results showed that the provision of the filter nearer the upstream side results in higher seepage losses and an increment in the required filter length. If the filter is located away from upstream face, i.e., near the downstream toe, though seepage gets reduced, the saturated zone is increased, resulting in a reduction of the dry zone. Comparison between two slopes 1V:1.5H and 1V:2H, shows the flatter the upstream slope, the farther location of the filter from upstream face. Trend in increasing of seepage, for drain length ratio = 0.66-1.25 (for 1V:1.5H) and for drain length ratio = 0.73-1.5 (for 1V:2H) are high. © 2013 Indian Geotechnical Society.