Behavior of sheet pile as seepage cutoff below earthen dam

Abstract

Seepage cut-off below an earthen dam is necessary for reducing seepage and thereby increasing its stability. In this study, analysis of an earthen dam has been done using FLAC 2D. The base width of the dam has been taken as 17 m width its side slope as 2(H):1(V). It has been considered to be an embankment dam made of homogeneous soil. The results of the analysis have been used to carry out a parametric study to observe the influence of sheet pile length and location on different design parameters, such as variation of pore water pressure, fluid flow vector, bending moment, and shear force. It has been found that increase in sheet pile length reduces flow vector, indicating the quantity of fluid flow is lesser for larger sheet pile length. An abrupt decrease in pore water pressure is found at the location of sheet pile. Bending moment in the sheet pile increases when sheet pile position moves toward the upstream side. For a fixed position of sheet pile, similar to bending moment, shear force is also appearing on positive side, when the length increases beyond 15 m. It has been found that although factor of safety against both piping and overall stability increases with sheet pile length, the piping phenomenon is more influenced as compared to the overall stability of dam.