Numerical Investigation of clay blanket effect in reducing leakage from foundation of embankment dams

In this study, to investigate the influence of clay blanket on reducing seepage a computer model has been developed in which general equation of fluid flow through soil has been solved numerically by finite elements method. At the end, a complete and comprehensive relation for the effect of clay blanket on leakage from foundation of dams has been presented. To do this, all effective parameters have been modeled by the SEEP/W 2012 software in 350 models. One of these important parameters is the horizontal to vertical permeability ratio in foundation that has not been applied in any other research so far. This ratio should have been calculated for giving a precise relation applicable in construction works. Other parameters include thickness, length and permeability ratio of the clay cover, foundation thickness and width of the core. In the following, the results of modeling by the SPSS 23 software have been analyzed and finally, the results of the proposed relation have been compared to the results of the software and relation of the American Army Civil Engineers. The result of this comparison testifies the completeness of the proposed relation and trivial difference with the results of the modelings. Based on the analysis, the effective length for the clay blanket four times the height of water behind the dam is proposed. Also, when thickness of clay blanket is low, the impact of different levels of permeability coefficient is almost identical in reducing leakage and permeability reduction of clay blanket is effective when its thickness increases.