In the past 25 years great strides have been made in the area of static stability and deformation analysis. The widespread availability of microcomputers has brought about considerable change in the computational aspects of slope stability analysis. Analyses can be done much more thoroughly, and, from the point of view of mechanics, more accurately than was possible without computers. Still, engineers performing slope stability analyses must have more than a computer program. They must have a thorough mastery of soil mechanics and soil strength, a solid understanding of the computer programs they use, and the ability and patience to test and judge the results of their analyses to avoid mistakes and misuse. Realistic analyses of deformations of slopes and embankments were not possible until about 25 years ago. They are possible now mainly because the finite-element method has been developed and adapted to these applications. The principal requirement for achieving reasonably accurate and useful results fro...

State of the Art: Limit Equilibrium and Finite-Element Analysis of Slopes

The search for the critical slip surface in slope-stability analysis is performed by means of a minimization of the safety factor. The procedures most widely used are deterministic methods of nonlinear programming, and random search methods have been neglected, since they are considered to be generally less efficient. In this paper, an efficient Monte-Carlo method for locating the critical slip surface is presented. The procedure is articulated in a sequence of stages, where each new slip surface is randomly generated by an appropriate technique. From a comparative analysis, the proposed method provides solutions of the same quality as the best nonlinear programming methods. However, the structure of the presented method is very simple, and it can be more easily programmed, integrated, and modified for particular exigencies.

Efficient monte carlo technique for locating critical slip surface

In probabilistic slope stability analysis, the similarity and differences of the surface of minimum factor of safety (FS) and the surface of minimum reliability index (β) have not been investigated fully. Probabilistic analyses have often been performed on the surface of minimum FS, and sometimes on an arbitrary surface. The surface of minimum FS and the surface of minimum β do not generally coincide. In this paper, an expedient technique is presented to search for the critical probabilistic surface utilizing existing deterministic slope stability programs. This technique is based on searching the critical surfaces obtained using specific combinations of soil parameter values. The critical probabilistic surface was found to generally coincide with that obtained by setting one dominant parameter to a low value. The technique is examined by a parametric study and applied to some case studies. It proved to provide a practical and efficient method to locate the critical probabilistic surface.

C.W. Lovell

Papers

Searching techniques in slope stability analysis