Centrifuge Modeling of Geosynthetic-Encased Stone Columns in Soft Clay under Embankment

Abstract

The failure mechanism of geosynthetic-encased stone columns (GECs) in soft clay under embankment is still far from clear. In this study, centrifuge modeling was performed on two different stiffness GECs under embankment. The soft clay used in the tests was made of sodium bentonite powder and glycerin with a 1:1 mixture ratio by mass. The undrained shear strength of the man-made clay is only 5.6 kPa. Two polymers with 123.4 and 13.6 kN/m stiffness were used in the tests. The test results show that the encased stone columns under embankment slope are bended outwards at approximately half depth of foundation. As it can be seen, the bending of the columns encased with low stiffness polymer was more apparent compared to the columns encased with high stiffness polymer. However, the failure mechanism of the GECs is different from that of the GECs in relatively stiff clay revealed by the authors before. In the authors' previous physical tests, the top of the encased columns in Kaolin clay under embankment bended outwards the largest. It can be concluded that the stiffness of soils between the columns may influence the failure modes of the GECs.