عنوان مقاله [English]
Improving of soil shear resistance of problematic soils is always one of the challenges for civil engineers. Uniform and incompressible sands is one of these soils. Nowadays, focused on environmental issues, economic issues and reuse of waste materials in civil engineering and choosing soil remediation methods is very necessary. In this article, the shear behavior of Neka sand with uniform granulation, which is stabilized using a polymer liquid called PAYTEX NL25 (with low environmental consequences) and reinforced with the waste fibers of tire thread, is investigated by conducting a series of Consolidated Undrained (CU) Triaxial Test. The percentage of polymer liquid was zero, 1, 2, 3 and 4 percent by weight and fiber was added to it by 2 percent of dry soil weight. Triaxial tests were performed under confining pressures of 100, 200 and 400 kPa. The samples were made at the maximum density and optimum moisture obtained from the standard proctor compaction test and were cured at 23 Celsius degree up to 270 days. In general, the results of the tests showed that the aforementioned polymer liquid has a good potential to stabilize granular soils, and as a result of stabilization, the resistance parameters and hardness of the soil are improved several times. So that, adding of 4% polymer to sandy soil, increases its cohesion from nearly zero up to 1350 kPa for the sample without fiber and 900 kPa for the fiber reinforced sample. However, the behavior of the stabilized samples are brittle and they generally break at strains less than 3 percent and undergo a lot of softening after the breaking point. The presence of fibers slightly increases the breaking point strain, but significantly makes the behavior of the sample more flexible after the breaking point and prevents the rapid drop in shear strength. Although the presence of fibers reduces the stiffness of the stabilized sample, still the reinforced stabilized sample is much harder and more resistant than the empty sand.