Shear behavior of geotextile-reinforced silty sand using static triaxial testing

Abstract

A total of 15 consolidated undrained triaxial tests were performed on samples with a size of 75 mm diameter and 150 mm height at three confining pressures of 50, 100 and 200 kPa for investigating the shear performance of nonwoven geotextile-reinforced silty sand and to study the excess pore water generation. The test comprises of zero, one, two, and three horizontal geotextile layers that were situated at regular vertical intervals inside the silty sand. Only one type of geotextile was utilized in all the tests. The results provide facts that as the confining pressure increases, the peak strength for the both case reinforced as well as in unreinforced samples increases. The results verified that the insertion of nonwoven geotextile reinforcement into sand-silt mixture enhanced peak deviator stress and shear strength parameters (c and ϕ), and reduce the loss of post-peak shear strength. Also, the usefulness of reinforcement on improving the net shear strength was evaluated using shear strength difference that is, the peak deviator stress difference between nonwoven geotextile-reinforced specimens and unreinforced specimens at a particular confining pressure. The results showed that strength difference decreased may reduce to zero at a certain reinforcement spacing (77–85 mm), which is equivalent to spacing diameter ratios of 1.02–1.13. For the geotextile-reinforced soil, as the number of geotextile layer increases, the strength improves due to the mobilization of larger tensile force at higher confining pressure. Also, the inclusion of geotextile layers restrained the horizontal displacement of soil. Failure patterns were visualized using Plaxis 2D finite element software for case of geotextile-reinforced silty sand specimen under axis symmetric triaxial loading.