Kuwar khairnar, Sintash Shivde

The effect of sample size is a phenomenon that involves the dependence of resistance on the size
of the tested sample, where smaller samples exhibit higher resistance compared to larger ones. Due
to the importance and sensitivity of determining the resistances of laboratory samples for use in
design, codes, and standards, efforts are made to minimize the effects of sample size. This issue
holds true for the design of reinforced soil structures. Given the cost and time-consuming nature
of laboratory tests and the desire to reduce costs, save time, and facilitate numerical modeling for
predicting soil behavior, there is a significant inclination towards numerical modeling.
In this study, after validating the computer model with numerical simulation of triaxial test results,
the effect of size was examined by constructing models with different sizes. The PLAXIS 2D
software performed this simulation in the axisymmetric pattern and analyzed one-fourth of the
total sample. All experiments were conducted on unreinforced cohesive soil with geotextile
reinforcement, subjected to confining pressures of 400, 600, 800, and 1000 kPa, with different
diameters (38, 100, 200, and 400 millimeters) and modeled with one to four layers of geotextile.
The presence of geotextile increases the maximum resistance, and this increase is more
pronounced at higher confining pressures and a greater number of reinforcing layers. The results
also indicate that decreasing the sample diameter leads to a decrease in confining pressure and the
distance between geotextile layers. However, for unreinforced samples and samples with diameters
larger than 400 millimeters, the size effect has no significant impact on the results.