Modeling of the small strain shear modulus on a fiber reinforced sand
Abstract
The mechanical behavior of fiber reinforced soils has been extensively
studied in the last decades. Previous studies have shown that inclusion of fibers
increases the shear strength of the reinforced soil. However in some cases the
presence of fibers can reduce the stiffness of the composite material. In this paper,
we study the change on the initial stiffness in an alluvial sand reinforced with
polypropylene fibers. A model based on Hertz elastic contact theory is developed
in order to explain the trends of the maximum shear modulus in the fiber
reinforced sand as the fiber content is varied. The model assumes that the shear
wave is transmitted through elastic distortions at the contacts, so the stiffness of
the contacts governs the initial shear modulus, which in turn is affected due to
fibers addition. Furthermore, the ratio between the amount of grain to fiber
contacts and the total of contacts on the shear wave path influence the maximum
shear modulus. An experimental testing program involving confined compression
tests with shear wave velocity measurements of unreinforced and fiber-reinforced
sand specimens was undertaken to validate the proposed model trends. The model
predictions were found to agree well with the experimental results.