A methodology based on GIS for 3D Slope Stability Analysis

Abstract

Abstract-In this paper, we present an analysis of slope stability using Geographic Information Systems (GIS). The methodology is based on the calculation of the safety factor in 2D and 3D using GIS. Hovland's Method in 3D and 2D have been used in the stability analysis of the slope located at the 34 kilometer point (KP.34) on the highway in the North of Morocco connecting Tangier to Ksar Sghir. Isohypse and the digital elevation model (DEM) of the studied site have been built from topographical surveys. Results shows that the safety factors (FS) obtained in 3D analysis are about 11 % higher than those obtained in 2D analysis and the slope becomes unstable when the water table level is below 1m. Keyword-Slope stability, GIS, Hovland Method I. INTRODUCTIONSlope stability problems are frequently encountered in the construction of roads, canals, dikes and dams. Moreover, some natural slopes are or may become unstable. Slope failure can be catastrophic and cause loss of life and considerable damage.The study of a slope includes, besides the recognition of the site and the choice of the mechanical characteristics of the soil, a stability calculation to determine firstly failure curve along which the slip risk is highest, secondly the corresponding value of the safety factor.Slope stability analysis is applied by two-dimensional 2D and three-dimensional 3D analyses. In slope stability analysis, it is clear that a three-dimensional situation may become important in cases where the geometry of the slope and slip surface varies significantly in the lateral direction, the material properties are highly anisotropic, or the slope is locally loaded [1].There are several methods of slope stability analysis in 2D and 3D: Limit equilibrium methods (LEM) and Finite Element Methods (FEM). Limit equilibrium methods have been the primary method used in estimating the stability of slope for decades ([2]-[3]).The basic principle of all these methods is to cut the volume of soil studied in a number of slices and apply different forces. The procedures are based on finding a Factor of Safety (FS) for the slope. It is useful to know exactly what percentage the 3D safety factor is higher than the 2D analysis.Since the middle of 70s, many 3D methods of slope stability analysis have been proposed; these methods are traditionally based on an extension of 2D Limit equilibrium methods analysis. The slicing method in 2D analysis has been extended into 3D analysis with columns by various authors due to the popularity of 2D LEM slicing methods. Hovland [4] analyzed a three dimensional slope stability using the method of columns. A new 3D slices method has been proposed by Ugai [5], to analyze 3D slope stability by extending the Fellenius method. Hungr [6] and Huang and Tsai [7] have proposed a three dimensional slope stability analysis method based on an extension of Bishop's simplified 2D method of slices.The 2D general limit equilibrium formulation (Fredlund and krahn [8] ) has been extended by Lam and Fredlund [9] to analyze a 3D slope stabil...

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Reassessment of the Stability Conditions in the Lignite Open Pits of Oltenia (Romania) in Relation to the New Local Seismic Context as an Imperative for Sustainable Mining

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