The Investigation of Salinity Effects on Behavioral Parameters of Fine-Grained Soils

The present paper aims at investigating the effect of water salinity on engineering properties of fine-grain soil. Saline water used in this study was obtained from half saline water of Ajichay River (with TDS more than 1877 ppm) and saline branch of Korchay (with TDS more than 97000 ppm) located in Northwestern of Iran. Fine-grain soil studied is from Korchay dam core. Due to the high hardness of water in this river, the feasibility of using saline water as the water required in clay core of the dam process has been studied in this research. The experiments were performed including Atterberg limits, standard compaction, consolidation, direct shear and dispersion. These tests were performed by using distilled water, half saline water and saline water on reservoir materials. Due to low percentage of clay minerals in the soil, the changes in engineering soil properties as salinity increases are negligible. However, the use of saline water reduces Atterberg limits, compression index (Cc), swell index (Cs(, coefficient of compressibility (av), coefficient of volume compressibility (mv) and causes slight increase in soil shear strength parameters. Despite the high percentage of sodium in half saline and saline water, dispersion degree of soil is ND2 in pinhole test

Effect of woven geotextile reinforcement on mechanical behavior of calcareous sands

The mechanical properties of calcareous sands are critical as potentially important material sources for marine geotechnical constructions. Brittleness and large deformations created in calcareous sands can affect the stability of marine structures and geosynthetic reinforcement is a promising new approach. In this study, a series of consolidated-drained (CD) tests were conducted to evaluate the mechanical properties and deformation of woven geotextile-reinforced calcareous sand. For this purpose, the effect of geotextile layers, relative density, type of woven geotextile, and confining pressure were investigated. The results show that the strength of the reinforced specimens increases markedly compared to the unreinforced calcareous sand and the deviatoric stress-strain curves change from slight softening to hardening and dilatancy. Also, by increasing the number of woven geotextile layers and applying a confining pressure, the shear deformation shifts toward strain-hardening behavior. Overall, woven geotextiles significantly improve the apparent cohesion strength of calcareous sand soil. The woven geotextile, relative density, and confining pressure all contribute to volumetric changes and dilatancy of reinforced specimens, but particle breakage is more affected by confining pressure