Behavior of Fabric‐Versus Fiber‐Reinforced Sand

TLDR

Triaxial compression tests compared sand reinforced with continuous, oriented fabric layers to sand with randomly distributed discrete fibers, varying reinforcement amount, confining stress, inclusion modulus, and surface friction. Both reinforcement types increased strength and axial strain at failure, reduced post‑peak loss, but fabric reduced compressive stiffness at strains <1%; strength rose proportionally with reinforcement up to an asymptotic limit, with fabric failing by bulging and fibers by planar shear.

Abstract

Triaxial compression tests were run to compare the stress‐strain response of a sand reinforced with continuous, oriented fabric layers as opposed to randomly distributed, discrete fibers. The influence of various test parameters such as amount of reinforcement, confining stress, and inclusion modulus and surface friction were also investigated. Test results showed that both types of reinforcement improved strength, increased the axial strain at failure, and in most cases reduced post‐peak loss of strength. At very low strains (<1%) fabric inclusions resulted in a loss of compressive stiffness. This effect was not observed in the case of fiber reinforcement. The existence of a critical confining stress was common to both systems. Failure envelopes for reinforced sand paralleled the unreinforced envelope above this stress. Strength increase was generally proportional to the amount of reinforcement, i.e., the number of fabric layers or weight fraction of fibers, up to some limiting content. Thereafter, the strength increase approached an asymptotic upper limit. Fiber‐reinforced samples failed along a classic planar shear plane, whereas fabric‐reinforced sand failed by bulging between layers.