As the cheapest materials, soils are used widely at the construction of earth fill structures. Therefore, various techniques have been employed to improve the soil shear and strength properties. Soil improvement techniques may be categorized into 5 groups including chemical, physical, mechanical, biological and electrical methods. Materials such as lime, cement, coal ash, enzymes and some types of polymers have been used as soil stabilizers, while soil reinforcement by geosynthetics, metal bars and polymers fibers used as physical technics to improve soil performance. One of the soil reinforcement applications is the construction of reinforced soil retaining wall. In this study, the performance of soil reinforced model walls has been investigated using braid elements as new tubular geosynthetics. The main purpose of this research is to consider on the effect of different parameters of the soil and braid elements on the performance of the reinforced soil retaining wall models. The parameters investigated in these models are the number of reinforcement layers (N), length of reinforcement (L), the diameter of the braid (D), the relative density of the sand (D r ), the slope of reinforcement elements. An attempt was also made to investigate the influence of covering the reinforcements with adhesive resins to enhance interface properties between soil and reinforcement elements. Moreover, the effects of type and shape of the reinforcements are investigated. Results obtained from this investigation showed the optimum reinforcement parameters were found as the length of reinforcement at 0.7H, braid diameter of 4 centimeter and reinforcement oblique of 10 degree. In addition, the use of the adhesive resin found to improve the performance of reinforced soil retaining wall. Moreover comparison between various geosynthetics shows that tubular braids were more appropriate regarding the performance of reinforced soil retaining walls. This improvement may be attributed to the fact that tubular braids mobilize high shear strength in the reinforced soil. Key Words Reinforced soil retaining wall, Braid element, Oblique reinforcements, Resinated braid
