Bearing capacity of geosynthetic encased stone columns

The benefit of using stone columns in low strength soil has been proved as an efficient method to improve load-carrying characteristics of shallow footings. The stone column bearing capacity mainly depends on circumferential confinement providing by native soft soils. In this paper, some large body laboratory tests were performed on stone columns with diameters of 60, 80, and 100 mm and a length to diameter of 5. Both unreinforced and encased geotextile reinforced stone columns were tested. Vertical encased stone column (VESC) have been considered to investigate the effect of reinforcement on the footing load-carrying characteristics. The main objective of this research is to compare the effectiveness of vertical encapsulating of stone columns in the same conditions for various stone column diameters. In addition, tests on groups of stone columns with 60 mm diameter were carried out to investigate the effect of presence of neighboring columns on the reference loaded stone column. Results show that the stone column bearing capacity increases by using vertical reinforcing material. With increasing the length and strength of reinforcement in VESC, the stone column bearing capacity increases. In addition, the stress concentration ratio of columns also increases. Moreover, the lateral bulging decreases by using geotextiles. Numerical analysis based on finite element method (FEM) was also conducted to study scale effects on small stone columns tested and how to expand reinforcement effectiveness to large reinforced stone columns.