Through different methods which are available for soft soil improvement today, stone columns are one of the most frequently used methods due to their low cost, effectiveness and ease of installation. In this method, usually fifteen to thirty five percent of weak soil volume is replaced by stone materials through opening up a vertical cylindrical hole in the soft clay bed and susiquently filling it up with compacted crushed or gravel. In order to increase the bearing capacity of sone columns is soft caly, the idea of reinforcing the stone columns with geosynthetics have been proposed. In this study the performance of braid encased stone columns have been investigated. The most different between braid and another kind of geosynthetics is cylindrical shape of braid that can make full encasement for stone columns. In this study the performance of braid encased stone columns and palanar geosynthetic encased stone columns has been comparised. Due to comparing the result of loading tests, a better performance of braid encased stone columns has been proved. The performance of braid encased stone columns will increase in higher amounts of loading. Then in the following, the effect of diameter, height to diameter ratio, hardness of incasement materials and also the length of the incasment materials has been investigated for braid encased stone columns. Stone columns performance improves with increase in diameter and height to diameter ratio due to replacement if soft soil with more hard crushed stones. Also, by examination of the time, the longer time interval between installation loading leads to more bearing capacity. This increase in bearing capacity is due to drainage of water by stone columns material which increase the undrained shear strength of soft caly. Finally, a number of tests has been performed on the group of stone columns and a comparison has made between the performance of the braid encase stone columns and the planar geosynthetic encased stone columns. Key Words Bearing Capacity, Stone column, Braid, Geosynthetic, Clay bed
