Numerical simulation using the finite element method to investigate the effect of internal cutoff walls on seepage and hydraulic gradients in homogeneous earth dams

The seepage reduction in embankment dams is essential to their stability and safety. This research aims to evaluate the effects of penetration depth (16, 18, 20, 22, 24 m), distance from the beginning of the crest width (0, 2, 4, 6, 8 m), and inclination angle (45 degrees, 90 degrees, 135 degrees) of the internal cutoff wall on some of the design parameters in an embankment dam using the Finite Element Method. It was found that the existence of an internal cutoff wall leads to a significant decline in the phreatic line level. Increasing the internal cutoff wall penetration depth decreases seepage flow so that the maximum decline in seepage flow rate is 39.7% for a penetration depth of 24 m. In contrast, by increasing the internal cutoff wall penetration depth, hydraulic gradient and relative drop in total head increases. In addition, as the distance of the internal cutoff wall from the upstream end of the crest width increases, the seepage discharge and hydraulic gradient increase. For a penetration depth of 22 m, the maximum decrease in seepage discharge was about 31.23% for x = 0 m. It was seen that by increasing the inclination angle of the internal cutoff wall, the maximum hydraulic gradient occurred in more downstream locations. An internal cutoff wall with inclination angle of 45 degrees and penetration depth of 24 m was found to have the best performance at reducing seepage by 49.7%. The relative drop in the total head reaches the maximum value with a cutoff inclination angle of 135 degrees.

Automated summary

This research evaluates the effects of penetration depth, distance from the beginning of the crest width, and inclination angle of the internal cutoff wall on design parameters in an embankment dam. The presence of an internal cutoff wall leads to a significant decline in the phreatic line level. Increasing penetration depth decreases seepage flow, while increasing distance from the crest width and inclination angle increases seepage discharge and hydraulic gradient. An internal cutoff wall with an inclination angle of 45 degrees and penetration depth of 24 m has the best performance at reducing seepage by 49.7%.