Numerical Analysis of Stone Column Installation in Soft Clay: Evaluation of Dynamic Effects

This study presents a numerical investigation into stone columns’ installation and post-installation behavior in soft clay. A parametric study was conducted to explore excess pore water pressure generation and bearing capacity enhancement. Five stone column configurations were simulated across two radial expansion ratios using the Cylindrical Cavity Expansion (CCE) method implemented in PLAXIS 2D. Results showed that dynamic installation process, simulating vibro-replacement, produced transient stress waves, inducing fluctuations in lateral earth pressure and excess pore water pressure immediately around the column. Moreover, the columns with larger diameters and lengths significantly enhanced the lateral confinement and generated higher excess pore pressures near the installation. The bearing capacity improved markedly within a radial distance of 1–3 times the column diameter, beyond which stress and pressure effects diminished rapidly. When the radial distance equals 0.35 m, the maximum lateral stress coefficient exceeded 3.4 with pore pressure spikes and a strong soil-column interaction. The decay in influence was consistent across all configurations, confirming a localized zone of improvement typically constrained within 6–8 times the column diameter. Finally, the study confirmed that larger expansion ratios and optimal column dimensions resulted in enhanced bearing capacity and controlled dissipation of pore water pressures. Overall, critical insights are provided for stone columns behaviour in soft clay under dynamic installation conditions.