Geotechnical behavior of encased stone columns in soft clay soil

Several techniques are currently available for improving soft clay soil properties. In this research, a finite element model (FEM) has been performed using the PLAXIS 3D program on a floating single stone column either without encasement as an ordinary stone column (OSC), or with an encasement as encased stone column (ESC). This study investigates the behavior of a single floating stone column and its radial deformation with two diameters (D = 0.4 m and 0.6 m). A series of (62) cases were carried out with different parameters like the length of encasement, and the strength of geosynthetic material, where the ratio of the length of the column to the diameter is kept constant at (L/D = 10) in all cases. From this study, bulging was observed to be initiated at a deeper length in the case of the (ESC) due to encasement. The bearing capacity of soil for (OSC) with D = 0.40 m has increased by about 60% compared to the case of clay only. While for the case of using (ESC), it is observed to be increased by 120% at Lenc/D equals 2. Moreover, for the case of D = 0.6 m, the bearing capacity of the (OSC) was observed to be increased by 33% compared to the case of clay only. While for the case of the (ESC), it was observed to be improved by 93%. The results show that there is an increase in the bearing capacity of the soil in the encased columns than in the untreated soil.