Investigation of the influence zone of stone columns with and without geogrid encasement by experimental and numerical studies

The influence zone for geogrid encased stone columns (GESC) and ordinary stone columns (OSC) were investigated in the scope of this study. For this purpose, a single stone column (OSC or GESC) was built in clay soil which was placed in tanks had various diameters to observe load-deformation behavior of a 5 cm diameter rigid model footing. The effects of the water content of clay soils on the behavior of stone columns were also investigated. This study consists of two stages. Firstly, experimental studies were conducted at the laboratory using model loading test setup, and secondly, models created with a finite element method (FEM) based software called as Plaxis and numerical analyses were carried. Experimental study results validated the FEM results closely for short-term stability. Therefore, further investigations on FEM models were carried out. As a result of this study, generally, geogrid encasement for the stone columns increased the bearing capacity and the decreased amount of lateral bulging and settlement. In addition, for OSC and GESC, the influence zone was about 5 and 6 times the stone column's diameter, respectively. So, it can be said that encasing the stone column with geogrid reduced the influence zone.