Dynamic Behavior of GESC Groups in Sand Under Sinusoidal Loading: A Continuum‐Discrete Coupled Analysis

ABSTRACT Geotextile‐encased stone columns (GESCs) for improving weak foundations commonly experience static and dynamic loads. However, the effectiveness of GESCs in resisting dynamic loading remains a concern. Three‐dimensional numerical models using a continuum‐discrete coupled method are developed to investigate the dynamic response of GESC groups in sand under sinusoidal loading. The models capture the dynamic variations in settlement ( δ z ), lateral displacement ( δ r ), porosity, coordination number, contact force distribution, and radial stress coefficient (). A parametric study further examines the effect of six key factors. The results reveal that the column group effect notably reduces δ r of the central column by 52.78% compared to a single GESC. GESCs exhibit shear deformation and translational movement, with δ r increasing as the distance from the group center grows. The position of maximum δ r shifts downward from a z/ D ratio of 0.83–2.5 with increasing distance in the x ‐direction, while remaining stable in the y ‐direction. High contact forces accumulate at the GESC bases, peaking initially before declining over time. The remains below 2.0, considerably lower than the passive earth pressure coefficient ( K p ). K p for design purposes overestimates the bearing capacity of GESCs under dynamic loading. GESC groups are more sensitive to lower loading frequencies, while larger relative density, soil strength, or column diameter improves dynamic resistance.