Soil improvement techniques are mostly cosisted of 5 groups including chemical , physical, mechanical, biological and electrical methods. Materials such as lime, cement, coal ash, enzymes and some types polymers are used for chemical stabilization, while geogrides, geotextiles, metal bars and polymer fibers are used to improve soil performance as the physical methods known as soil reinforcement. Several techniques have been used for soil reinforcement. In 1966, Vidal first used galvanized steel strips to improve the properties of cohesionless soils. Since then, numerous reinforced earth structures have been constructed throughout the world. One of the reinforced soil applications is the construction of reinforced soil retaining walls. The major advantages of the reinforced soil walls are their flexibility and absorbency of deformations. Regrading experiences derived from previous studies, it was first attempted to investigate the effect of facing slope, oblique reinforcements and reinforcements anchoring on the performance reitaning wall by experimental and numerical approach. The improvement ability of soil reinforcement orginates mostly from the interface strength between the soil and the reinforcement elements. Thus the in the second part of this study, an attempt was made to investigate the influence of covering the reinforcements with adhesive emulsions to enhance interface properties between soil and reinforcement elements. In this section, the direct shear tests were used to determine the interface shear strength parameters. Physical models of reinforced soil retaining walls with such renforcement elements were also constructed and loaded to consider their peroformance. The results of first part showed that reinforced soil wall with oblique reinforcements of 10 degree and inclined facing of 80 degree significantly reduce the maximum horizontal deformation of the surface. These results are shown agree reasonably well with the results of numerical analyzes. The results of direct shear tests showed that setting time more than 24 hours for geotextile impregnated with adhesive emulsion are not properly. As expected, the interface friction angle of the reinforced sand (with adhesive emulsion) was found to be more than that of the unreinforced sand. In addition, the use of the adhesive emulsion helps to improve the performance of reinforced soil retaining wall. KEYWORDS Reinforced soil, Oblique reinforcements, Inclined facing, Reinforcements anchor, reinforcements coating.
