It’s about one decade that the technique of reinforcing soil slopes with vertical geosynthetics has been presented. Many theoretical and experimental studies have been performed in these reinforced geotechnical structures. In the reported experimental works on vertically reinforced soil slopes, arching phenomenon has been observed and reported. Theoretical studies have indicated that the consideration of arching effects increases the safety factor against failure, significantly. In this research the arching effects in both horizontal and vertical directions in the vertically reinforced slopes are considered by the use of common approaches of soil slope analysis. At first, the shape and position of three dimensional slip surface are determined by consideration of arching effects and then the safety factor is calculated by the conventional limit equilibrium method. In this method, uniform surcharge on the crest of slope, pore water pressure and the horizontal pseudo statical seismic loading can be considered. By considering the arching, the failed wedge is smaller, so with controlling both the size of wedge and safety factor, it is possible to reach the optimum design for slopes with vertical geosynthetic reinforcements.
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