Development of a GIS-Based 3D Slope Stability Analysis System for Rainfall-Induced Landslide Hazard Assessment

The assessment of landslide hazard should give answers to three key questions: the location, the magnitude, and the occurrence time of potential failures. This paper proposes a GIS-aided 3D methodology for quantitative assessment of regional landslide hazard and prediction of the three key questions. A revised 3D slope stability model is developed by coupling a dynamic rainfall infiltration model with a 3D limit equilibrium approach. To define the study object of the 3D model in regional assessment, an automatic methodology of slope-unit division is developed by using GIS hydraulic analysis functions. The location and shape of unknown slip surface(s) are identified by means of minimizing the 3D safety factor through an iterative procedure, based on a Monte Carlo simulation for the 3D shape of ellipsoid. Executing the searching calculation for each slope unit during rainfall can result in changing distribution of the critical slip surface(s) as well as their occurrence time related with rainfall. Incorporating all proposed methods, a standalone GIS system, called 3D slope stability analysis GIS system (3DSSAGS), is developed based on the Component Object Model technology. In this system, all the professional analyses are embedded within GIS for efficient use of GIS functions.