This investigational study was directed to establish the correlation between piled raft foundation and two soil improvement techniques, stone columns and lime columns to evaluate the bearing improvement ratio BCR for the soft clay soil with three values of undrained shear strength, 8 kPa,10 kPa and 12 kPa. The 12 model tests was conducted in the present work, three models of untreated soil, three models of soil with piled raft, three models of soil treated with stone columns and three models of soil treated with lime columns. The container used in experimental works was made of steel with plane area of 500 mm * 500 mm and 500mm in height. The thickness of soil sample inside the container was 400 mm.
The study showed that the piled raft was more efficient in the bearing capacity improvement than the two soil improvement techniques. The bearing improvement ratio were 3.39, 3.27 and 2.78 in the three model tests of piled-raft for three samples of soil, respectively, while the lime columns provided the lowest values of the bearing improvement ratio were 1.64, 1.67 and 1.8 respectively.