Effect of Initial Stress Anisotropy on Small-Strain Properties of Fiber-reinforced Calcareous Sand

Abstract

This research presents the effects of using glass fibers as an eco-friendly additive on the small-strain properties of calcareous sand, commonly found in coastal and land reclamation areas. A series of resonant column tests were conducted on Hormoz calcareous sand, reinforced with randomly distributed glass fibers, under isotropic and anisotropic stress conditions. The results showed that glass fibers increased the small-strain shear modulus. Moreover, with increasing confining pressure, the optimal fiber content decreased from 2% to 1% (by weight). The damping ratio slightly decreased with 2% fiber content but increased with 1%. Overall, both shear modulus and damping ratio were increased with an appropriate amount of glass fiber reinforcement. The results of all tests indicated that initial stress anisotropy increased the shear modulus. However, fiber content and initial stress anisotropy had a negligible effect on the normalized shear modulus. In this study, an empirical relationship was also proposed to estimate the ratio between the maximum shear modulus under anisotropic and isotropic stress conditions. This relationship was validated using a comprehensive laboratory dataset, and it was found to depend only on the initial stress anisotropy and to be independent of confining pressure, fiber content, particle shape, or void ratio.