Abstract: Combined with the assumption of normal stress distribution on sliding surface and the spatial analysis capability of Geographic Information Systems (GIS), a three-dimensional (3D) slope equilibrium model based on grid cells is established, and a GIS-based slope stability calculation method is proposed. In this method, a 3D slope stability analysis model based on grid cylinder elements is firstly established, and the spatial computational expression of each parameter in GIS is clearly articulated. Secondly, under the condition of limit equilibrium, a set of stability analysis equations, including three force equilibrium equations and one moment equilibrium equation of the sliding body, are derived for solving the three-dimensional safety factor. Finally, following the Mohr-Coulomb strength criterion and the assumption of normal stress distribution on the sliding surface, the three-dimensional safety factor is solved. Moreover, the component object model (COM) technology is used to develop a GIS-based 3D slope stability analysis module, which can be implemented for the complex algorithms and the calculation of multiple stratigraphic slopes and multiple combinations of factors in 3D slope stability analyses. The correctness and feasibility of the module are verified by three typical cases.

Key words: GIS, slope stability analysis, limit equilibrium, normal stress on slip surface, component object modet (COM)