A Comprehensive Study of Different Types of Seepage Control Measures for Earth Dam Using FEM

Abstract

Dam failure involves a huge amount of economic, financial, structural losses as well as loss of numerous number of lives and properties. All most all earth dams are subjected to seepage problem. In most instances, seepage failure of earth-fill dams occurs because of inadequate seepage control measures. Due to seepage, the pore water pressure inside the dam increases which makes the dam unstable. Excessive gradient causes boiling effect while seepage discharge causes loss of water in storage reservoir. Moreover, due to seepage, problems like sloughing, piping, blowing out of dam materials, erosion of dam toe, sand boiling and slope failure occurs. As the seepage through the earth dam is difficult to stop, proper control measures must be adopted to save any hydraulic structure such as earth dam from failure. This paper has performed a comprehensive study of the incorporation of different seepage control measures to an earth dam using Finite Element Method (FEM). SEEP/W, a FEM based software, has been used for modelling and analysis of different seepage control measures. From the numerical analysis, it is observed that use of rock toe combined with horizontal filter is more beneficiary than they are used alone. The length of horizontal blanket filter is a controlling factor to reduce the pore water pressure rather than its thickness. Horizontal blanket filter comprises of coarse sand layer at top and fine sand layer at bottom turns out preferable results for all flow properties. Performance of inclined rock toe is better than vertical rock toe to reduce pore water pressure and gradient. It is also noticed that trapezoidal shape of internal clay core is better than other shapes of the internal clay core considered in this study. Moreover, it performs more efficiently if transition filter is adopted.