Small scale behavior of stone columns encased by tires

Stone columns are one of the best-suited methods of ground improvement for sites consisting of soft clays, silts and silty sands. Stone columns need to be supported against bulging failure as the main reason that reduces their bearing capacity. Disposal of scrap tires is one of the principal environmental problems around the world. Therefore, the reuse of scrap tires has grown globally. This paper investigates the behavior of stone columns encased by scrap tires which has the potential of replacing other encasements. Stone columns with diameters of 66, 80 and 92 mm which are one-tenth of original tire sizes have been tested in a large box, and the load-carrying characteristics of them are analyzed. Based on the results, by increasing the diameter of the encasement stone column, the benefit of the encasement increases. In addition, tests on the groups of stone columns with a diameter of 66 mm were carried out to investigate the presence effects of neighboring columns on the reference load. Furthermore, a comparison has been made with the results of ordinary stone columns and encased stone columns with geotextile to obtain the benefits of scrap tire columns. The bearing capacity of both single and group of stone columns encased with the scrap tire increases more than the ordinary stone columns. However, the bearing capacity of geotextile encased stone column is more than the other groups. Further, numerical analysis has been conducted to implement full-scale reinforced columns. The results illustrate that using scrap tires reduces bulging failure and increases the bearing capacity of stone columns. Accordingly, scrap tires replace the geotextile (as usual encasement) because their amount of bearing capacities are similar to each other especially in columns with larger diameters.