Effect of Core Geometry on Earth Dam Slope Stability

Abstract

Embankment dams are widely constructed due to their suitability with different types of foundation, and it is constructed from the available material at the site. A zoned earth dam consists of a clay core at the center to control seepage supported by a shell. This paper investigated the impacts of side slopes, top width, and shape on upstream and downstream slope stability during different cases. Slide 6.0 software was used to evaluate the factor of safety of side slopes of an earth dam, and its result was validated. Different side slopes range from 0H:1V to 2 H:1V, and crest widths from 3m to 10 m were examined. In addition, for the slanting core case, several cases with varying angles of inclination were provided. The results indicated that by increasing the side slopes of the core, the factor of safety was reduced, especially in the steady state and rapid drawdown conditions. Increasing the top width also reduced the safety factor in the steady state condition. This reduction was because the core material had lower shear strength than the shell material. In addition, in a steady state and rapid drawdown conditions, the cohesion of core material sharply reduced. Compared with the vertical case, increasing the slanting core slopes influenced the slope stability insignificantly during the steady state. The slanting core had benefits in the steady state when the reservoir was full since, in this case, increasing core side slopes affected the slope stability insignificantly. The maximum core side slope in the earth dam and maximum top width, which insignificantly affected the dam’s slope stability, were 0.8:1 and 5 m, respectively.