Document Type : Research Article

Authors

• Yalda khastoo ¹
• Hojjat Ahmadi ²
• mohammad hemmati ²
• Bahram nourani ³

¹ Daneshkadeh Street, First Alley, towards Ma’navi Alley, Engineers Building, Unit 24

² West Azerbaijan – Urmia – Urmia University – Water Engineering Group

³ East Azerbaijan – Tabriz – 29 Bahman Boulevard – Imam Khomeini Street – University of Tabriz

Abstract

This study numerically investigated the seepage behavior of a non-homogeneous earth dam equipped with a pipe drain and a clay blanket over a permeable foundation. A total of 324 two-dimensional seepage models were simulated using SEEP/W, with independent variables including the anisotropy ratio (K_y/K_x=0.5,1,1.5), drain position (horizontal X_L=7,11,15,19" " mand vertical Y_L=18.5,20,21.5" " m), clay blanket length (L=17,34,51" " m), and drain diameter (d=0.1,0.2,0.3" " m). Multiple regression analyses showed that the developed models for total seepage discharge, drain discharge, and downstream outflow had strong statistical performance, with coefficients of determination of R^2=0.978, R^2=0.756, and R^2=0.809, respectively. The results indicated that the vertical drain position had the most significant negative effect on collected seepage, while the horizontal position had a positive effect. The anisotropy ratio and drain diameter showed no significant influence within the tested range. From a hydraulic perspective, installing the pipe drain lowered the phreatic surface, reduced pore-water pressures near the downstream toe, and decreased the exit gradient, improving hydraulic stability. Increasing the clay blanket length significantly reduced seepage, but further increase beyond a certain limit provided only marginal improvement. Overall, the clay blanket length and vertical drain depth were identified as the most critical parameters for optimal seepage control in non-homogeneous earth dams.

Keywords

• Non-homogeneous earth dam
• pipe drain
• clay blanket
• seepage
• SEEP/W

Main Subjects

• Hydraulics