3D parametric analysis of embankment settlement reduction using geosynthetic-encased stone columns with radial expansion

Purpose This study aims to present a comprehensive investigation into the settlement behavior of geosynthetic-encased stone columns (GESC) installed in soft clay soils beneath embankments. Particular emphasis is placed on evaluating the combined effects of geosynthetic reinforcement and the installation method of a group of encased columns – especially the lateral expansion technique – on overall ground deformation. Design/methodology/approach A series of advanced three-dimensional numerical simulations were performed using the PLAXIS three-dimensional finite-element software, with validation against field data from the Penchala Toll Plaza project. A detailed parametric study explores the influence of key factors, including lateral expansion (ranging from 0% to 10%), geosynthetic stiffness and column arrangement (triangular vs square patterns), on settlement performance. Findings Results indicate that while the lateral expansio`n technique primarily influences the deformation pattern, geosynthetic encasement provides the most significant reduction in settlement and lateral bulging. Increasing the stiffness of the geosynthetic material further enhances load-bearing capacity and limits vertical displacement. The observed rise in hoop strain resistance and stress concentration ratio confirms a more efficient transfer of load to the stone column core when encasement is applied. In addition, both the friction angle of the column material and the adopted column layout play a decisive role in controlling settlement. Improved horizontal displacement resistance and accelerated pore-pressure dissipation further demonstrate that the combined reinforcement system (VGESC + HGRSC) offers the most balanced enhancement across settlement performance, drainage and deformation control. Originality/value This research distinguishes itself by incorporating the radial (lateral) expansion installation method in conjunction with geosynthetic encasement, a combination rarely explored in previous studies. The findings offer valuable insights into optimizing material selection, reinforcement design and installation strategies for improving embankment settlement performance over very soft clay soils, thereby contributing meaningfully to the field of ground improvement and geotechnical engineering.