Earth Slopes Subject to Lateral Acceleration

Equations are derived that satisfy the equilibrium conditions for both forces and moments for earth slopes subject to lateral acceleration. The equations are applicable to any shape of failure surface and take into account the effect of interslice forces whose slope may vary from slice to slice. Two methods of solving the equations are given: One uses the value of the factor of safety as variable; the other uses the critical value of the lateral acceleration factor. In both methods, the second variable is a factor controlling the slope of the interslice forces. Problems are solved which indicated that: (1)A logarithmic spiral failure arc is not more critical than a circular arc; (2)the stability is reduced if the lateral acceleration has a downward component; and (3)taking the factor of safety and the acceleration factor as alternative criteria, the critical slip circles are fairly close—provided that the cohesion of the soil is small.