Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 55 2 2023 04 21 Effect of Soft Lens on the Behavior of Ordinary and Reinforced Stone Columns Located in Saturated Sandy Bed Effect of Soft Lens on the Behavior of Ordinary and Reinforced Stone Columns Located in Saturated Sandy Bed 455 470 5036 10.22060/ceej.2023.21390.7711 FA NIYOUSHA Bazazzadegan Department of Geotechnics, Faculty of Civil Engineering, Islamic Azad University, Science and Research Branch Navid Ganjian Assistant Professor of Science and Research branch of Azad University Javad Nazariafshar Assistant Professor, Department of Civil Engineering, Shahr-e-Qods Branch Islamic Azad University, Tehran, Iran 0000-0001-8807-1417 Journal Article 2022 05 20 One of the effective methods to improve the behavior of problematic beds containing soft lens is using stone columns. The capability of this soil improvement method increases by simultaneous use of the stone column and geosynthetic encasement, especially in the presence of soft lens near the ground surface or where the possibility of bulging failure is probable. In this research, the efficiency of using stone column embedded in a saturated sandy bed containing soft lens has been numerically investigated in terms of bearing capacity and failure mode. Also, the efficiency of reinforcing the stone column has been investigated in the presence of soft lens with different thicknesses and placement level. The results of numerical analysis obtained by finite element software (Abaqus) and validated by laboratory results of small-scale physical model experiments in real stress conditions shows that in the presence of soft lens, the change in the length of a stone column does not affect the occurrence of bulging failure and decreasing placement level of the soft lens, increases the bulging failure occurrence proportional. On the other hand, increasing the thickness of the soft lens reduces the bearing capacity of the ordinary and reinforced stone column. The phenomenon of bulging can occur at the level of the lens placement and up to a depth of about 4 times the diameter of the ordinary column because of the<em> </em>existence of a soft lens in a relatively loose sandy bed, while the<em> </em>mechanism of failure is not bulging anymore if using encasement. One of the effective methods to improve the behavior of problematic beds containing soft lens is using stone columns. The capability of this soil improvement method increases by simultaneous use of the stone column and geosynthetic encasement, especially in the presence of soft lens near the ground surface or where the possibility of bulging failure is probable. In this research, the efficiency of using stone column embedded in a saturated sandy bed containing soft lens has been numerically investigated in terms of bearing capacity and failure mode. Also, the efficiency of reinforcing the stone column has been investigated in the presence of soft lens with different thicknesses and placement level. The results of numerical analysis obtained by finite element software (Abaqus) and validated by laboratory results of small-scale physical model experiments in real stress conditions shows that in the presence of soft lens, the change in the length of a stone column does not affect the occurrence of bulging failure and decreasing placement level of the soft lens, increases the bulging failure occurrence proportional. On the other hand, increasing the thickness of the soft lens reduces the bearing capacity of the ordinary and reinforced stone column. The phenomenon of bulging can occur at the level of the lens placement and up to a depth of about 4 times the diameter of the ordinary column because of the<em> </em>existence of a soft lens in a relatively loose sandy bed, while the<em> </em>mechanism of failure is not bulging anymore if using encasement. https://ceej.aut.ac.ir/article_5036_c731077c04035ac9e92a3706288db18f.pdf