a new method for three dimensional stability analysis of earth slopes

In this research, a new threedimensional limit equilibrium method was developed. in the proposed method, the slip surface was assumed to be spherical and slices were assumed along the slip surface radius converging to a point. moreover, force and moment equilibrium equations were used. in order to calculate factor of safety (fs) with the proposed method, a code was developed for two and threedimensional state. the model uses the iteration (trial and error) method to simultaneously satisfy force and moment equilibrium equations. in order to ensure convergence of the numerical model developed in the three dimensional state, the under relaxation method used in the trial and error operations. in examples, the proposed method was obtained the value of fs, 2.5 to 12 percent higher than other methods. in order to validate the proposed method and assess the functionality of the three dimensional numerical model a few examples were solved under different circumstances and the results were properly compliant with the results of other methods.