جستجوی مقالات مرتبط با کلیدواژه "clay soils" در نشریات گروه "عمران"

In some regions with hot and dry climate conditions, the temperature varies greatly between day and night. Therefore, the materials used in construction projects are exposed to a large number of thermal cycles daily. In this research, the application of sodium alginate polymer as an eco-friendly additive for soil stabilization and improvement of its geotechnical characteristics is studied. The study involves conducting geotechnical tests on both control and stabilized soil samples (with and without sodium alginate polymer) such as standard compaction test, swelling tests, and measuring Atterberg limits, while specimens were subjected to the same temperature variations as those recorded in the Khuzestan province, in the southwest of Iran. In fact, this study aims to investigate the effect of temperature ranges on the changes in the swelling potential of high plasticity clayey soils stabilized with sodium alginate polymer. Consolidation tests were carried out on compacted clay samples - containing different concentrations of sodium alginate polymer with treatment durations of 1 and 14 days - in accordance with method C of ASTM standard. The temperature range considered in this research was 23 to 45℃ due to the simulation of the temperature in Khuzestan province in the spring and autumn seasons. Observations indicated an increase in the swelling potential up to %13 in a sigmoidal manner with the repetition of temperature ranges and the stabilization of swelling changes, or so-called aging of swelling, which occurs with the repetition of temperature fluctuations. Additionally, the samples were analyzed using X-ray Diffraction (XRD), and X-ray Fluorescence (XRF) techniques to investigate the changes in their compositions. These methods revealed the formation of palygorskite minerals in specimens. This mineral intensifies the soil's swelling potential and is considered one of the contributing factors to the observed increase in swelling in the stabilized soil samples containing sodium alginate polymer.

For assessing the consolidation settlement, it is mainly used by Terzaghi and Janbu theories. Main of this study is evaluation of the Janbu settlement modulus in clayey soils based on shear wave velocity with using down hole test. In continue, results with using artificial neural network analyses and statistical methods verified. The study area is The city of Tabriz is located in the northwestern part of Iran and has a variety of clayey soils, silty and marl types (yellow, green and gray) with different consolidation potential. In this research, by drilling three machine boreholes at depths up to 8 meters, complete physical, plasticity and consolidation experiments were carried out on 20 undisturbed samples. The in-field Downhole test was also used to determine the shear wave velocity in the boreholes. Moreover, shear wave velocity was evaluated in study area with using down hole test and based on effective vertical stress on study depths normalized. Results showed that the Janbu settlement modulus and normalized shear wave velocity in study area respectively are between 14.38 to 41.39 and 234 to 694 m/s. With considering that results of existing practical relationships for determining the Janbu settlement modulus were not appropriate in study area. In order to improve the practical relationships between the Janbu settlement modulus and normalized shear wave velocity artificial neural network and statistical methods with applying linear, logarithmic and exponential functions was performed. Results showed that exponential function for determining the Janbu settlement modulus in study area is favorable.

Basic Divergent clay soils are soils that have high percentage of sodium ions.The soils prone to leaching when placed under water seepage and erosion. In this research, the impact of crude oil as a side effect of pollution (possibly positive) on the amount of divergence of the soil will be discussed. Therefore, first soil artificially by adding a solution of sodium hexametaphosphate were divergent and then some pinhole test on soil samples with different amounts of crude oil diverged (1, 3, 5 and 7%) were performed. In addition to this, the effect of crude oil pollutants on the shear strength and uniaxial testing was conducted to help. Results obtained showed that with presence of oil and increase in percentage of oil and the time of soil and oil contact, dispersivity of soil decrease. Thus with gradual increase of oil, the territory is quite divergent soil became non-divergent. Also the,single pivot (uniaxial )tests experiments showed that at the first samples strengths increase to 3% oil content and more oil quantities reduces the the resistance of the soil.