Numerical Evaluation of Sample Size Effect on the Behavior of Undrained Geotextile-Reinforced Cohesive Soil

Size effect, a phenomenon that is related to the dependence of the strength to the sample size that leads to more strength in the small samples compared to large samples. present study was carried out to investigate the effects of sample size on the mechanical behavior and geotextile-reinforced clay features in the short time using the PLAXIS 2D software. These simulations were modeled for different confining pressures: 400,600,800 and 1000 kPa and different diameters: 38, 100, 200, 300, 400 and 600 mm and one to four geotextile layers. Two constitutive models including the Moher-Coloumb model and hardening soil model are used to simulate the behavior of the soil. The results indicate that the hardening soil model forecasts more realistic pattern of soil behavior and values obtained from this model are always less than the results of Moher-Coloumb model.In unreinforced soil, the sample size effect is negligible, but in reinforced samples considerable for each confining pressure and number of geotextile layer, the effect up to a diameter of 400 mm and after that, any changes in sample size have no effect on results. Therfore, 400 mm diameter sample size can be used for behaviour of reinforced clay soils in short-term conditions. In other words, using a sample with a diameter of 400 mm instead of 38 mm diameter a real values is proposed for shear strength parameters reinforced clay soils in short-term conditions.