UNIAXIAL COMPRESSION TESTS OF BIAXIAL GEOGRID-ENCASED STONE COLUMNS

In this paper, stone columns are encased with three types of biaxial geogrid such as stretch plastic geogrid, welded polyester geogrid and knitted polyester geogrid. Uniaxial compression tests are conducted on the geogrid-encased stone columns to study their deformation and strength characteristics. The results show that there are good linear relationships between column strength and encasement strength both in stretch plastic geogrid and knitted polyester geogrid encased columns, while the linear relationship is not good in welded polyester geogrid encased columns. Stretch plastic geogrid encased column is damaged when the strength of geogrid reaches, while welded polyester and knitted polyester encased columns are damaged due to the breakage of welding or knitting nodes when the strength of geogrid are far from reaching. Therefore, the strength of stretch plastic geogrid encased column is significantly higher than that of welded polyester geogrid and knitted polyester geogrid encased columns. In practical engineering, stretch plastic geogrid is recommended for encasing the stone columns, and the strength of plastic geogrid-encased stone columns can be calculated by using a corrected theoretic formula for polypropylene geotextile encased stone columns.