Slope Stability Analysis by Swedish Slip Circle Method Using C-Programming

Abstract

The side slopes of an earthen dam should be safe against shear failure. Out of the various methods of stability
analysis of slopes, “Swedish Slip Circle Method” is commonly used in practice. Here in the Swedish circle
method, potential failure surface is assumed to be cylindrical in shape (i.e., circular in cross section). After
determining the actuating and resisting forces for assumed failure surface, the factor of safety is calculated. The
slope is considered safe if the minimum factor of safety is greater than the specified value. This paper aims at
presenting the procedure for determination of factor of safety using C-program. The program helps to calculate
normal component (N) and tangential component (T) at a faster rate as compared to graphical method. With the
use of co-ordinate system for determination of normal and tangential components, the program results in a very
accurate value which will otherwise be approximate, if calculated by graphical method. The program also
displays N-plot, T-plot and U-plot which are important features of rectangular plot method. Another important
feature of the program is the graphical representation of cross section of the dam along with assumed slip
surface and number of slices with different forces acting on them. This paper aims at comparing the value of
factor of safety obtained by graphical method with that obtained by C-program. With this computational
approach, the obtained factor of safety is more accurate than that obtained by conventional graphical method.
Keywords: N-plot and T-plot, factor of safety, rectangular plot method, normal and tangential components,
slope stability, graphical method