OPTIMAL GEOGRID WEIGHT AND FAILURE MODES OF GEOGRID ENCASED STONE COLUMNS UNDER AXIAL COMPRESSION LOADING WITH COST CONSIDERATIONS

Abstract

This study investigates the efficiency of geogrid encasement in stone columns under axial compression loading, with a focus on cost-effectiveness and performance. A three-dimensional finite element analysis is conducted using PLAXIS 3D to evaluate the ultimate bearing capacity, lateral displacement behavior, and failure mechanisms of encased stone columns (ESCs). The load-settlement response and lateral displacement profile along the column depth are analyzed to determine the optimal geogrid encasement configuration. The results indicate that, for a fixed geogrid weight, a thinner but longer encasement significantly enhances the ultimate bearing capacity and minimizes lateral displacement compared to a thicker but shorter encasement. Furthermore, three primary failure mechanisms under axial compression loading are identified: column head failure, column body-soil interaction failure, and soil failure, with the governing failure mode dependent on column geometry and encasement parameters. Based on these findings, the study proposes an optimal geogrid weight guideline for ESC applications, offering a balance between material efficiency and performance. Additionally, a design chart is developed to illustrate the relationship between ultimate bearing capacity and geogrid weight, providing engineers with a systematic approach for preliminary ESC design. These insights contribute to advancing cost-effective and high-performance geotechnical solutions using ESCs, optimizing their application in ground improvement projects.