Effect of Varying Geometrical Configuration of Sheet Piles on Exit Gradient and Uplift Pressure

Seepage becomes an inevitable concern when dealt with earthen dams, as the impounded water seek paths of least resistance through the dam and its foundation. Seepage, if uncontrolled, can erode soil from the embankment or foundation causing progressive or rapid erosion and piping of the embankment or foundation soils. Out of the several approaches, increasing the length of the flow path by using sheet piles has proved to be effective in seepage reduction. This study examines the effect of using multiple sheet piles of varying length positioned at different distances from the upstream and downstream of a homogeneous earthen dam on the variation of exit gradient, uplift pressure, porewater pressure, and flux along the toe of the dam. The analysis is done using a Finite Element modeling with the aid of SEEP/W module in Geo-Studio 2007 software. The results of the numerical analysis gives an insight about the effect of varying geometrical arrangement of the sheet piles on the reduction of exit gradient, uplift pressure, porewater pressure, and flux along the downstream portion of the dam during the reservoir filling condition. The study highlights the arrangement of the sheet piles to obtain the maximum reduction of exit gradients and porewater pressures during the rise-up condition.