The study of the behavior of non-cohesive soils, also called granular soils, is one of the most important areas in geotechnical engineering for several reasons. These soils are characterized by the lack of adhesion between their particles. Understanding the behavior of a non-cohesive soil, under different stress conditions, helps to avoid problems related to geohazards. Among the most important of these problems are soil liquefaction, erosion, landslides, and collapses. It has been revealed that these phenomena are generally caused by dynamic natural hazards, such as earthquakes. In this study, an experiment was carried out on a reduced model of an undrained, non-cohesive soil, with two relative densities, loose and medium-dense, and with a variation in the saturation degree of soil reinforced with synthetic fibers. The experimental results obtained in the laboratory were recorded and analyzed to examine and assess the influence of these fiber additions on the resistance of sand in vibrational mode. It should be mentioned that the percentage of incorporated fibers was chosen after the characterization of natural (unreinforced) and reinforced sand, in static mode, on a triaxial path. Moreover, the influence of fiber additions on improving the sand's mechanical parameters was assessed and analyzed in dynamical mode, based on the accelerations that were generated during the Chi-Chi earthquake in Taiwan (1999). Finally, it is important to note that the relationship between the final relative density and the saturation degree have a direct impact on the mechanical behavior of soil.