Numerical Analysis of Seepage and Slope Stability in an Earthen Dam by Using Geo-Slope Software

Abstract

The present research work was conducted to compute seepage and slope stability analysis of Hub dam (earthen dam) by using the slave programs of Geo-Slope software i.e. SEEP/W and SLOPE/W respectively. The simulation results obtained from the SEEP/W program revealed that the average flow rate of seepage at maximum, normal and minimum pond level were 5.728 x 10^-4 (ft³/sec/ft), 4.988 x 10^-4 (ft³/sec/ft), and 4.513 x 10^-5 (ft³/sec/ft) respectively. The exit gradient value in all different pond levels was less than 1.0, and maximum seepage velocity is within permissible limits, which implies that the dam is secure against piping for the entire scenarios. SLOPE/W program was used to analyze static slope stability of embankment slope under various loading conditions. The stability of embankment slopes was checked by four different analysis methods i.e. Bishop, Janbu, Ordinary method of slice and Morgenstern-Price method accordingly. The simulation results revealed that upstream and downstream side of the dam section has a direct effect on the factor of safety. The three different loading cases were analyzed i.e. end of construction (upstream and downstream slope), steady state seepage (downstream slope) at maximum water level at EL 346 ft, and rapid drawdown for (upstream slope) with the minimum factor of safety 1.653, 1.911, 1.634 and 1.766 respectively. From the results achieved, thus it can be concluded that the Hub dam is safe against the danger of piping and slope failure.