Calculation of Bearing Capacity of Geosynthetic-encased Stone Columns

The bearing mechanism of composite foundation of geosynthetic-encased stone columns was analyzed,and several kinds of failure mode of the composite foundation were investigated.In different failure modes,according to the limit equilibrium theory,a calculation formula of the ultimate bearing capacity of single geosynthetic-encased stone column was proposed.Failure mode 1 is mainly controlled by the tensile strength of geogrid sleeve,and failure mode 2 is controlled by the pile-lateral friction of geosynthetic-encased stone column and the end bearing capacity of common stone column before the damage of swelling deformation.The example of calculation indicates that the(1) bearing capacity of geosynthetic-encased stone column has significantly improved than that of common stone column;(2) the reinforcing depth of geosynthetic-encased stone column and the tensile strength of geogrid sleeve have a best combination for the most rational using of geogrid to improve the bearing capacity of the stone column.At last,the geosynthetic-encased stone columns were applied to treatment of weak subgrade of expressway.