Numerical and experimental modelling of seepage in homogeneous earth dam with combined drain

In this study, the use of combined drain has been suggested as an alternative for triangular toe drain in a homogeneous earth dam. The main idea used in this research is to reduce the volume of drain materials that are manufactured and simultaneously achieving better hydraulic performance. To study this idea, at first, the hydraulic performance of the combined drain and the influence of replacing the triangular toe drain with this type of drain is investigated using the small-scale physical modelling. Then large-scale numerical simulation was performed by developing a numerical model. The designed triangular toe drain height was reduced by 20, 30, 40 and 50%, and part of the remaining material was placed horizontally alongside the reduced triangular toe drain. The results showed that using combined drain with similar hydraulic performance to triangular toe drain models, saved 18 to 60% on the volume of drain materials for the models provided. Finally, the appropriate dimensions of combined drain are proposed based on the saving of material used. At the end, by applying dimensional analysis method, the dimensionless charts are presented to estimate the seepage quantity through the section of the homogeneous earth dam with combined drain. © 2021 Indian Society for Hydraulics.