GEOSYNTHETICS-ENCASED SAND COLUMNS TO IMPROVE COMPRESSIBILITY AND BEARING CAPACITY SOFT SOIL PERFORMANCE

Soft soils, typically derived from Pliocene-Holocene sedimentation, are characterized by high clay mineral content and significant moisture, leading to low shear strength and prolonged consolidation time, which pose significant challenges in civil engineering construction. To address these issues, this study investigates the use of geosynthetic enchased sand columns (GESC) as vertical drainage systems and load-bearing elements to improve the mechanical properties of soft soil. The sand of sand drain, as a granular material, facilitates consolidation acceleration and increases soil shear strength. Sand as granular columns increases the bearing capacity of soil. The experimental program involved permeability tests, direct shear tests, and unconfined compressive strength tests for core material evaluation, along with consolidation tests for column and soil interaction, and triaxial tests for consolidated soil performance. The study assessed GESC configurations with varied diameters and spacings in a modified consolidation device (20 cm diameter cylinder) and a box setup (20 × 20 cm with 3 cm column spacing). Experiments were conducted with diameter variations of 3 cm, 4.58 cm, 6.7 cm, and 8.55 cm and spacing variations of 2D, 2.5D, 3D, and 4D with a diameter of 3 cm. The results indicate that the optimal configuration comprises GSCE with a diameter of 4.85 cm and spacing of 9 cm (3D), achieving enhanced consolidation rates and shear strength. These results suggest that geosynthetic-encased sand columns effectively improve soil stability, bearing capacity, and deformation control, thereby making them suitable for soft soil conditions in infrastructure projects like road embankments and foundations.