Toward standardizing the search for critical slip surface in slope stability analysis

Slope failures are among the natural disasters that cause casualties and serious damage worldwide. Limit equilibrium method is often used to calculate the factor of safety of a given slope, where a feasible and practical slip surface is assumed to define the mechanism of failure. Researchers apply different optimization techniques to determine the most unstable slip surface, but the importance of establishing an appropriate standard for the search parameters has been rarely investigated. This paper reviews the most respected research in this field, perceives their assumptions and limitations, and elaborates on the structure and geometry of their search parameters. Built on a comprehensive literature review, a standard guideline is proposed for the search parameters. The required steps to construct different slip surfaces are discussed and a standard reporting format is introduced. The proposed guideline is expected to contribute to improvement of the reliability of the slope stability analyzes and provide a base for fair comparison between the results of different studies.