Mobilization of Reinforcement Forces in Fiber-Reinforced Soil

Fiber reinforcement represents a promising alternative in projects involving localized repair of slopes and reinforcement of thin soil veneers, where planar reinforcement (e.g., with geotextiles and geogrids) is difficult to implement. Current design methodologies allow quantification of the shear strength of fiber-soil composites in terms of the parameters that independently characterize the soil matrix and fibers. The shear strength of fiber-reinforced soil is considered to have two components, including the shear strength of the soil matrix and the tension mobilized within the fibers. Triaxial compression tests and fiber pullout tests were conducted to evaluate how the fiber tension is mobilized for varying shear strain levels. The results of this evaluation provide insights into whether the shear strength of fiber-reinforced soil is governed by the peak or residual shear strength of unreinforced soil. A revision to existing design methodology is proposed in which the individual contribution of fibers and soil matrix is quantified based on the strain level. The appropriateness of using the peak or residual shear strength of the unreinforced soil for predicting the equivalent shear strength of fiber-soil composites is discussed based on strain compatibility considerations.