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Author: Admin | 2025-04-28
Factor of safety [5]. A factor of safety value of less than 1.0 implies that the slope is unstable [5, 6]. There are numerous methods for assessing slope stability, which can be broadly grouped into the following categories: the limit equilibrium method, numerical analysis, artificial neural network and limit analysis methods [5]. Numerical methods include the finite element method and the distinct element method, whereas the limit equilibrium method includes Fellenius’ method, Bishop’s method, Spencer’s method, Janbu’s method, etc.The suitability of these methods depends on slope characteristics, geological conditions, the presence of discontinuities, etc. For example, slopes with complex geometries comprising of non-homogeneous material characteristics or soil stratification coupled with complex mechanical soil responses (e.g. post-failure, strain softening and progressive failure) may be better approached via numerical analysis methods [6]. Slopes with simple geometries consisting of homogeneous materials can be analysed via the limit equilibrium method.The limit equilibrium method is the oldest method for determining the factor of safety of slopes. It is purely based on the principle of statics, in which the force and/or moment equilibrium must be satisfied [7, 8]. For example, Fellenius’ method satisfies the moment equilibrium condition but not the force equilibrium condition. Bishop’s method satisfies the moment equilibrium and vertical force equilibrium conditions but not the horizontal force equilibrium condition. Spencer’s method is a more rigorous method that satisfies all three conditions of equilibrium: horizontal and vertical force equilibrium and moment equilibrium [9]. All three methods assume a circular slip surface [9]. The Bishops method has been widely accepted as one of the best methods of limit equilibrium for calculating the factor of safety of circular slip surfaces [10].There are various advantages of using the limit equilibrium method over the finite element method. This method is much simpler than other methods [11,12,13,14] and is not
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