A Heuristic Search Method for Critical Slip Surfaces with Weak Layers

In slope stability, weak layers are thin layers of low-strength materials which can potentially form part of the critical sliding surface. The search for the critical slip surface in slope stability is a complicated optimization problem that minimizes the factor of safety by altering the parameters corresponding to the geometry of a slip surface. While searching for the critical slip surface, it is important to fully consider the weak layers in a model. Traditionally, slope stability programs have handled weak layers by clipping the slip surfaces, which are generated during the automatic searching stage, to the weak layers. If multiple weak layers touch a slip surface, there are multiple permutations of clippings that can be performed on the slip surface by the weak layers using any, all, or none of those weak layers. As such, it can become very difficult to identify which combination of the weak layers would produce the lowest factor of safety. In this paper, a new method is proposed which efficiently considers the contribution of each weak layer via an additional optimization parameter. The proposed approach is demonstrated via an example and is shown to be relatively faster in speed against leading industry methods, while maintaining comparable accuracy.