A Comprehensive Study on the Mechanical Performance of Geotextile-Wrapped Stone Columns under Triaxial Stress Conditions: Experiment, Numerical Simulation, and Analytical Model

This study presents a comprehensive investigation into the mechanical performance of geotextile-wrapped stone columns (GWSCs) under triaxial stress conditions, integrating experimental testing, numerical simulation, and analytical modeling. A coupled discrete element method and finite difference method numerical model is developed to capture the granular behavior of the stone column and the progressive tensile softening and rupture of the geotextile. Realistic gravel morphology and gradation are incorporated. The model is validated against laboratory triaxial compression tests, showing excellent agreement in stress–strain response and failure modes. Macro–meso scale analysis reveals a four-stage deformation mechanism: (1) initial compression governed by confining pressure; (2) transition to geotextile-dominated constraint; (3) critical dilatancy where axial stress continues to increase under stable confinement; and (4) postpeak failure initiated by geotextile rupture and resulting in rapid capacity loss. Force chain network analysis demonstrates that geotextile confinement promotes radial strong force chains and axial anisotropy, which collapse upon rupture. An analytical model is proposed based on these insights, incorporating a stress concentration coefficient to improve prediction accuracy. The model effectively reproduces the stress–strain behavior of GWSCs. Parametric studies further show that the confining pressure and relative density significantly influence strength and stiffness, while the geotextile tensile strength controls peak resistance and the modulus affects deformability. The results offer both theoretical understanding and practical guidance for the design and optimization of GWSCs in soft ground engineering, especially where deformation control and geosynthetic performance are critical.