Effects Of Stone Column Installation

Lateral soil displacements caused by stone column installation can be estimated using analytical methods. These analytical methods have been used to assess lateral movements measured during installation of single stone columns and generated by installation of a group of columns. The analytical methods were able to closely match lateral displacements during installation of single stone columns but were less accurate for group installation. Excess pore pressures generated by installation of the group of stone columns was also measured and the peaks could be reasonably approximated using analytical methods. Installation of the group of columns was also simulated using finite element methods. A numerical model based on in-situ and laboratory test data produced similar results to the analytical methods. Refinement of the parameters to better fit the measured data required a four order of magnitude increase in the permeability. It is speculated that such an increase in permeability is created by fracturing of the soft clay during installation of the stone columns. A finite element limit analysis was performed to assess whether the soft clay would be squeezed into the columns. The results of the assessment suggest that it is unlikely that the soft clay would penetrate further than about 2 rows of stone particles.