Static Response of Sands Reinforced with Randomly Distributed Fibers

TLDR

The study aims to determine the static stress‑strain response of fiber‑reinforced sands through triaxial compression tests and to develop a statistical composite‑strength model predicting fiber contributions under static loads. Laboratory triaxial compression tests were conducted on sands with randomly distributed fibers, and a statistical theory‑based composite‑strength model was formulated to predict fiber contributions under static loads. Randomly distributed fibers markedly increase the ultimate strength and stiffness of sands, with the magnitude depending on sand granulometry and fiber characteristics, and the composites exhibit either curved linear or bilinear failure envelopes whose critical confining stress decreases with finer gradation, higher angularity, and larger aspect ratio but rises with fiber modulus; the statistical strength model predictions align well with experimental results.

Abstract

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.