Deformation Analysis of Geotextile-Encased Stone Columns

Abstract

Based on the unit-cell concept, analytical solutions are presented to predict deformation behaviors of geotextile-encased stone columns at any depth below the top plane of the columns. Under vertical loads at the tops of the stone columns, an axial compression deformation occurs that is often accompanied by a lateral expansion near the top. This deformation characteristic of stone columns was incorporated directly into the proposed analytical method. The shear stress between the encased stone column and the surrounding soil in the vertical direction also was taken into account. In this method, the confining pressure provided by the soil was analyzed based on an analogy with passive earth pressure. The method was verified via comparison with two other analytical solutions. Parametric studies were conducted to investigate the effects of geotextile encasement, vertical applied stress, and column spacing and diameter on the deformation behaviors of columns. The results indicated that geotextile encasement with higher stiffness has a beneficial effect on reducing column bulging and settlement. Moreover, selection of geotextile stiffness for encased stone columns should be done in relation to column diameter and spacing because increased column diameter and decreased spacing have a great effect on settlement reduction.