Seepage through earthen dams under different dam geometries and conditions

Abstract

The study presents a method to carry out a new equation for the seepage rate of homogeneous earth fill dam with clay core using various geometry conditions. For this purpose the Slide 6.0 software has been used. The proposed program runs for (85) different geometrical cases of dam body to determine the seepage rate. The aim of the study is to examine the capabilities of slide 6.0 software in computing the rate of seepage and to find the impact of different structure geometry (e.g., upstream horizontal blanket length and thickness and, cutoff depth) on the reduction of the rate of seepage through the proposed earth dam.

Dimensional analysis is conducted using Buckingham π theorem to find the dependent and non-dependent variables. Artificial Neural Network (ANN) model is developed that relates the output variables with the input variables which govern the rate of the seepage through homogenous earth dam with clay core. The results are analyzed using SPSS software.

Three different heights of the dam, three different lengths of the upstream blanket with four different thickness of the blanket and four different cutoff depths with different conditions were used in this study and the results showed that the rate of the seepage decreased as the upstream blanket length, the cutoff depth and the thickness of the blanket are increased. Also, the impact of the upstream blanket length is greater than the cutoff depth and then the thickness of the blanket in decreasing the rate of seepage. While, the rate of the seepage were increased as the top width of the dam were decreased.

The seepage rate obtained by the Slide 6.0 program was compared with its quantity calculated from an empirical equation developed in this study. This relation has a determination coefficient of (R² = 0.8842).