Abstract: A model experiment is conducted to study the bearing mechanism of geosynthetic encased stone columns. Bearing capacity, end resistance, deformation, destruction of the columns with different stiffnesses and lengths of encasements are analyzed. The radial deformation of the columns is measured by self-made radial deformation measurement instruments in the experiment. It can be found from the experiment results that the fully encased stone columns effectively improve the bearing capacity and stiffness of the stone column installing on hard soil layer. And the one with a larger modulus of elasticity of encasement material has the higher bearing capacity and stiffness. However, the partially encased stone column with an encasement length of 60% of the column length does not have significant advantages over the stone column. This is because the load capacity characteristic, deformation property, and failure mode of the fully encased stone column are different from those of the partially encased stone column. The load transmitted to the fully encased stone columns tip is higher than that of the partially encased stone column and the stone column. The deformation along the fully encased stone columns distributes more uniform compared to that of the partially encased stone column. And the maximum radial deformation along the fully encased stone column is lower at a certain pressure. What's more, the fully encased stone columns fail from penetrating into the upper cushion; while the uncased part of the partially encased stone column undergoes excess bulging.

Key words: geosynthetic encased stone column, model experiment, soft clay, encasement