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Slope stability is a major concern among geotechnical problems due to subsidence of the retained soil material. The factor of safety is an indication of whether a slope is safe or not, minimum values and other standards are normally stipulated by regional regulations. In order to prevent slope collapse an optimum design of gabion mesh wire with nails fixed into the withholding material is one of the prime solutions to this problem. However, different design methods for practical design of these cages exist. In slope stability problem, two-dimensional analysis is commonly used for simplicity though all slope failures are in three dimensional (3D) in nature. Until now, there, there is lack of detailed investigation on the optimum nail design that is cost efficient in a slope. This thesis aims at investigating the optimum length, number of nails, angle of inclination and profile of nail arrangement on a slope under different ground conditions by comparing the output results of MIDAS and GEO-SLOPE through their factor of safety (FOS) in the strength reduction and limit equilibrium methods (SRM/LEM) analysis.Both LEM and SRM are conducted in this study, and some interesting differences between these two methods are discovered. It is concluded that both methods have their own merits and limitations, and a good understanding of these methods is required before a good solution can be obtained.In this study, it was also found that Using these two major methods of analysis, no major differences were found in the location of the slip failure surface by LEM and SRM but some minor differences were found in the factor of safety between the two methods. From the FOS point of analysis, it was found that the maximum FOS is obtained when the maximum number and nail length is reached. In the analysis of the angle of inclination of the nails the best angle that satisfies both LEM/SRM was found to be between 10°-30°. But the optimum angle of inclination for both LEM/SRM was found to be 20°. The optimum layout of the soil nail was found to be longer at the top and bottom and shorter in the middle or longer at the bottom and shorter at the top, which is contrary to some researcher’s guidelines for soil nail design during top-down construction.With the detailed study on slope stability analysis using LEM/SRM a clear and better understanding on the optimum nail design in a slope has been achieved.