Static Response of Sands Reinforced with Randomly Distributed Fibers

Laboratory triaxial compression tests are performed to determine the static stress‐strain response of sands reinforced with discrete, randomly distributed fibers, and to observe the influence of various fiber properties, soil properties, and test variables on soil behavior. In addition to the experimental program, a model is developed, based on a statistical theory of strength for composites, to predict the fiber contribution to strength under static loads. Randomly distributed fiber inclusions significantly increase the ultimate strength and stiffness of sands. The increase in strength and stiffness is a function of sand granulometry (i.e., gradation and particle size and shape) and fiber properties (i.e., weight fraction, aspect ratio, and modulus). The sand‐fiber composites have either a curved linear or a bilinear failure envelope, with the break occurring at a threshold confining stress called the “critical confining stress.” The magnitude of the critical confining stress decreases with an increase in sand gradation, particle angularity, and fiber aspect ratio, and increases with an increase in fiber modulus. The critical confining stress is insensitive to changes in sand particle size and fiber content. Predicted strength increases from fiber reinforcement using a theoretical model based on a statistical theory of strength for composites agree reasonably well with measured values.