Analysis of seepage in the conditions of increased reservoir capacity by raising the spillway level (Case study: Kamal-Saleh earth dam).

Seepage is one of the main threat for the stability of earth dam, which can weaken the dam structure and cause piping, washing the earth dam materials inside the body or foundation and eventually its failure. In this study, seepage analysis of Kamal-Saleh earth-dam was performed using Seep/W software for current dam and increased spillway level. The effect of increasing the height of spillway on the seepage rate inside the body and foundation, hydraulic gradient and phreatic surface was investigated. To evaluate the dam behavior in the conditions of increasing reservoir capacity, seepage analysis was performed for current level and increased levels of spillway by one meter intervals. According to the results of software, the dam was safe against seepage in the current spillway level and provided the required factors of safety. In the conditions of increased spillway level, the amounts of seepage and hydraulic gradients increased and the factors of safety against boiling decreased in a way that by increasing the dam spillway level equal to 4 meters, the seepage through the dam body and foundation increased 85% and the safety factor against boiling decreased 4.5% but in all these conditions, the dam was safe against boiling. In the current and increased spillway levels , there are appropriate similarity of phreatic lines produced by the selected analytical method and Seep/W. The most similarity is seen in the upstream shell and core and the maximum difference is seen in the phreatic line intersection with the downstream slope of the dam.