A STUDY OF GEOSYNTHETIC ENCASED STONE COLUMN USING FINITE ELEMENT APPROACH

Abstract

Geotechnical engineers encounter various challenges and troubles while designing a structure over soft soils. These comprise of potential bearing failure, large lateral pressures and uncontrollable settlement and movement, and local or global instability. Geosynthetic encased system provides a more effective and reliable solution for the construction of various structures over soft soils especially during rapid construction or strict deformation of structure is required; such as embankments, retaining walls, storage tanks etc. The use of stone columns is popular as a ground-reinforcing technique for supporting flexible structures on soft to very soft soils. When the stone columns are installed in extremely soft soils, the lateral confinement offered by the surrounding soil may not be adequate to form the stone column. Consequently, the stone columns installed in such soils will not be able to develop the required load-bearing capacity. In such soils, the required lateral confinement can be induced by encasing the stone columns with a suitable geosynthetic or by placing horizontal strips of geosynthetics within the columns at regular intervals. In this study a three dimensional numerical analyses, using finite element technique (ABAQUS) is carried out for simulating the response and behavior of an ordinary versus encased stone column installed in a soft soil. A numerical analyses is performed using Mohr-Coulomb’s failure criterion considering elasto-plastic behaviour for soft soil and stone column. Load-Settlement response is selected as a criteria to compare the performance of ordinary versus encased stone columns. Also, parametric analyses is carried out to study the effect of stiffness of geosynthetic and diameter of stone column. The results indicate that the performance of the columns enhances, by increasing the tensile stiffness of encasement and observed that there isn’t much of a difference in the load-settelement response of ordinary stone column of varying diameters.