Numerical investigation of the optimum location for a drainpipe through a zoned earth dam.

Earth dams are massive structures mostly built from soil-based materials, and an essential aspect of geotechnical engineering is thus managing seepage through earth dams. The quantity of water flowing through earth dams can be computed utilizing the principle of flows through pored materials, and putting drainpipes through an earth dam is thus a common practice to reduce both seepage flow (Q) and exit gradient (ie), as well as to increase the slope stability of the earth dam by increasing the factor of safety (FS). This study used a finite element method (FEM) to solve the equations of flow through a hypothetical model of a zoned earth dam. Steady-state seepage analysis was thus performed, based on an impervious foundation assumption, with the soil media considered isotropic. To conduct this analysis, GeoStudio 2018sub-programs SEEP/W and SLOPE/W were used: SEEP/W was used to evaluate the seepage analysis, while SLOPE/W was used to analyse the slope stability. The diameter of the drainpipe selected was 15 cm, and the horizontal location (S) of the drainpipe was chosen from among seven relative positions (S/B=0.1, 0.2, 0.3, 0.4, 0.7, 0.8, and 0.9). The vertical location was set to 1 m from the base of the earth dam in all cases. The findings showed that when the drainpipe was placed near the upstream, it was ineffective, while a drainpipe placed downstream was significantly effective in reducing both Q and exit gradient ie, as well as increasing the FS. The optimal location of the drainpipe was found when the relative location (S/B)= 0.7, based on minimum values for Q and exit gradient ie, as well as producing a maximum value for FS. When the drain was placed at the optimal location (S/B=0.7), the decreases in Q) and ie were 99.2% and 99.5%, respectively, while the increase in the FS was 8%. [ABSTRACT FROM AUTHOR]