عنوان مقاله [English]
Since most natural deposits are a combination of sand and fine grains and as man-made geotechnical structures like tailing dams have a high percentage of cohesive and cohesionless fine grains, so the study of cyclic and post cyclic behavior of these soils is essential. For saturated sands, the effect of non-plastic fine grains (silts) on its monotonic and cyclic behavior has been investigated. The majority of studies are related to monotonic and cyclic loading, and post-cyclic loading has received less attention. In this paper, the effect of silt content and different Cyclic Stress Ratios (CSR) on the cyclic and post-cyclic behavior of saturated loose sand are investigated. The sand used in this study is Firuzkuh silty crushing sand which is abbreviated to sand 161. All samples are prepared so that the relative density of samples after the consolidation is about 30%. The experiments are performed using the saturated cyclic triaxial apparatus. Suitable preparation of specimens is one of the most important factors in the accurate performing of triaxial tests. Various sampling methods have been proposed that can be used depending on the type of soil and loading. Since cyclic and post cyclic tests are performed on a mixture of sand with different silt percentages, for making samples, the uniform compaction method has been considered as one of the proposed methods of sample preparation in ASTM standard. Changes in pore pressure coefficient, liquefaction resistance, stress-strain curves and stress path in clean and silty sand (10% silt) have been considered. Results show that the tested samples become liquefied in a smaller number of cycles by increasing the CSR until they show softening behavior at larger CSR when effective stress rapidly reduces to zero. In lower CSR, the stress-strain curve is collapsible while in larger CSR, loops expand that indicates more damping of material.