Drawdown Analysis of Slopes by Numerical Method

A numerical procedure is used to analyze slopes subjected to transient free surface seepage. The procedure combines a finite element scheme with a method of slope-stability analysis. The finite element scheme allows computations of time dependent locations of free surface, and the stability analysis method permits computation of factor of safety. The final results are plotted in terms of charts expressed through a number of nondimensional quantities. It is found that the value of the lowest factor of safety by the proposed procedure is approximately equal to that from the conventional assumption of sudden drawdown. The procedure can be found to be more economical if the designer can adopt drawdown ratios less than unity. The numerical procedures can provide an improved understanding of the behavior of slopes during transient drawdown conditions.