IMPROVEMENT OF SOFT CLAYS BY END BEARING STONE COLUMNS ENCASED WITH GEOGRIDS

Abstract

In this paper, the finite element method is utilized as a tool for carrying out different analyses of stone column–soil systems under different conditions. A trial is made to improve the behaviour of stone column by encasing the stone column by geogrid as reinforcement material.

The program CRISP2D is used in the analysis of problems. The program adopts the finite element method and allows prediction to be made of soil deformations considering Mohr–Coulomb failure criterion for elastic-plastic soil behaviour.

A parametric study is carried out to investigate the behaviour of ordinary and encased floating stone columns in different conditions. Different parameters were studied to show their effect on the bearing improvement and settlement reduction of the stone column. These include the length to diameter ratio (L/d), end support of the stone column and the area replacement ratio (a_s).

It was found that the effect of encasement length ratio on bearing improvement and settlement reduction increases with the increase in the end bearing soil undrained shear strength.

The encasement of the stone column should be extended to the full stone column length to make the stone column take the full benefit of the end bearing soil support especially for long columns with (L/d) more than 4