A REVIEW ON EFFECTS AND CONTROL OF SEEPAGE THROUGH EARTH-FILL DAMSeepage normally occurred in the dam when water infiltrating slowly through the dam and its foundation.
Inadequate seepage control measures have incurred many seepage problems and failure of earth-fill dams.Uncontrolled saturation and seepage forces was on of the main causes of earth dam failures. Therefore, the assessment to phenomena such as drawdown, which occur in earth structures subjected to sudden changes of water level that modify flow conditions inside a soil mass, should be done. Besides the factors that incurred seepage are the erodibility of the soil, the water velocity inside the soil mass and the geometry of the earth structure. Other important factors are the anisotropy of the earth structure and its foundation soil, the soil graduation and degree of compaction of the materials used during the construction process, the hydraulic conductivity of such materials, the upstream water energy head, as well as the hydraulic gradient.When the soil resistant forces are less than the seepage forces, then the soil erosion will occur, causes by the water flow removed and carried the soil particles away. The soil resistance forces depend on the cohesion, the interlocking effect and the weight of the soil particles with these factors this will be able to protect the soil particle from the downstream. The erosion phenomenon increases where there exists a concentration of seepage and water velocity; in places where this concentration emerges at the downstream side, the erosive forces on the soil particles might become very significant.
The erosion might probably starts at any point where the seepage water discharges and works toward the reservoir, gradually enlarging the seepage channel. Depending of the stage of this process, the occurred damage might be classified as a simple “incident”, an accident, or a complete failure.