Application of GIS Tools for Three-Dimensional Slope Stability Analysis of Pre-Existing Landslides

摘要

In the United States alone, landslides are estimated to cause an annual loss of about $1.5 billion and at least 25 fatalities, with much more damage occurring around the world. Therefore, analyses of previous and potential landslide regions are of great interest. Currently, there are a number of different software programs and methods being utilized for slope stability analysis to evaluate the safety margin of a slope. These methods range from the more commonly used simplified 2D method, to the more time consuming 3D method (each of these can produce a slightly different safety factor value). In this research, a new approaches to both 2D and 3D slope stability analysis have been implemented that utilizes ArcGIS Spatial Analyst, and the ArcGIS 3D Analyst extensions in calculating the factor of safety of a pre-existing landslide located in the Ilam district of Nepal. Tracing out the contours for ground geometry, sliding surface, and water table gave a 3D rendering of the physical surfaces. Those surfaces were utilized to perform both 2D and 3D slope stability analyses. The calculated factors of safety from each method were compared. The study result shows that mid-section was not a critical section for 2D slope stability analysis. A section located at the right side from the mid-section exhibited the lowest factor of safety.