In earthen dam engineering, one of the primary methods for seepage control involves implementing various drainage systems in the downstream region. This study presents a comprehensive evaluation of multiple drainage configurations through an extensive series of numerical simulations conducted using SEEP/W software. The analysis focuses on assessing the influence of different geometries and dimensions of downstream drains. Initially, the simulation results were validated against available experimental data and prior numerical studies, demonstrating satisfactory agreement and confirming the reliability and accuracy of the modeling approach. The analysis of the outcomes indicates that the length of the horizontal drain is the most critical parameter in reducing seepage, whereas the drain thickness has a comparatively minor effect. According to the findings, an optimal ratio of L/B ≈ 0.34 yields the most favorable hydraulic performance for horizontal drains. Moreover, variations in the angle of the toe (claw) drain exhibited minimal influence on seepage reduction, suggesting it cannot be considered a primary design parameter. The study also compares the performance of inclined and vertical chimney drains, revealing that the inclined configuration demonstrates superior efficiency due to its enhanced capacity to direct flow paths, reduce pore pressure, and improve dam stability. Overall, this research provides practical, numerically based insights that can assist engineers in the design and selection of effective drainage systems aimed at minimizing seepage risks in earthen dams. Furthermore, the results highlight the strong analytical capabilities of SEEP/W in modeling seepage behavior and investigating alternative drainage design scenarios.
Aghamajidi et al. (Tue,) studied this question.