The Impact of Cut-off Wall Length on Seepage Characteristics of a Non-Homogeneous Earth Dam Evaluated with a Geo-Slope Finite Element Software

Abstract

Embankment dams have better stability than homogeneous earth dams, resulting in a slimmer design in volume. The core zone, which serves as an impermeable zone, is where embankment dams are weak. Zonal core embankment dams are a composite of several material characteristics. Due to the intricacy of the geometry, the material parameters, and the boundary conditions, drainage and geometric design will have an impact on seepage and phreatic line properties. In this study three geometric models of a non-homogenous earth dam (Hub dam) depict along with three different scenarios i.e. (i) original design, (ii). Dam with a partial cutoff wall, (iii). Dam with a full cutoff wall was numerically analyzed by using Geo-Slope (SEEP/W) software. The results indicate that the cutoff wall at its original shape and design performs better as the minimum seepage value of order 2.2117 x 10^-4 (ft³/sec/ft) with an exit gradient of (0.099) and minimum seepage velocity 1.0020 x 10^-6 (ft/sec) at 270 ft reservoir level. Any increment in the length of cutoff wall will be uneconomical as it does not make much difference to minimize seepage flux, seepage velocity, and exit gradient. For the majority of flow characteristics, the cutoff wall's length plays a very limited role therefore, it can be said that the Hub Dam has operated efficiently since its construction in accordance with its original form and design.