Seyed Vahid Mojtahed Sistani - Master’s Student of Foundation and Soil Mechanics, Department of Civil Engineering ,College of Engineering, Central Tehran Branch, Islamic Azad University, Tehran, Iran.
Soheil Ghareh - Department of Civil Engineering, Payame Noor University, P.O. Box ۱۹۳۹۵-۴۶۹۷, Tehran, Iran
Mehdi Siavoshnia - Faculty Member, Department of Civil Engineering, College of Engineering, Central Tehran Branch, Islamic Azad University, Tehran, Iran.

In this paper a laboratory study has been carried out on the effect of changing the type of soil filling cylindrical reinforcing elements from SM to GM on behavior of sandy soil. In this study the primary tests for evaluation of the impact of reinforced sand and gravel columns with diameters of 5 cm and heights of 15 cm subjected to vertical stresses of 50, 100, and 150 KPa were carried out in a large-scale direct shear apparatus (300×300×150 mm). Results showed that the shear stress and settlement of the reinforced sample with geogrid and a gravel column increases by 45.4% and decreases by 23.9% respectively compared to the non-reinforced sample.

Reinforced Column, Large-Scale Direct Shear Apparatus Test, Shear Stress, Settlement