Abstract
A landslide is a three-dimensional movement of a mass of earth and rocks, involving a limited length and width of the mass. Stability of a landslide can be discussed more comprehensively if it is rendered three-dimensionally. Simplified three-dimensional stability analysis is a quasi three-dimensional method using the expanded results of stability calculation of two-dimensional cross-sections for the evaluation of landslide stability. This method can be executed by using existing spreadsheet and two-dimensional slope stability calculation software. This paper describes the geometric modeling scheme of the simplified three-dimensional stability analysis method and also discusses a series of analysis procedures on the basis of example analyses. The results of the analyses have compared favorably with the results of the methods proposed by Hovland (1977) and J. Erik Loehr (2004) . The authors believe that the simplified three-dimensional stability analysis method can be used to estimate the magnitude of three-dimensional effects when no other three-dimensional method is applicable, though the calculation estimates approximate values.
