ABSTRACT
This chapter discusses numerical analysis methods to calculate the factor of safety without pre-defining slide planes. Many limit equilibrium programs exist to determine factors of safety for slopes. These execute very rapidly, and in the case of the method of slices for circular failure, use an approximate scheme in which a number of assumptions are made, including the location and angle of interslice forces. The chapter presents typical safety factor analyses for the most common discontinuum failure modes in rock slopes. All rock slopes involve discontinuities. Representation of the discontinuities in numerical models differs depending on the type of model. There are two basic types of models: discontinuum models and continuum models. Discontinuities in discontinuum models are represented explicitly—that is, the discontinuities have a specific orientation and location. Discontinuities in continuum models are represented implicitly, with the intention that the behavior of the continuum model is substantially equivalent to the real jointed rock mass being represented.
