Seismic Performance of Stone Column and Geosynthetic-Encased Stone Column Groups in Liquefiable Sandy Soils

Liquefaction is one of the most destructive geotechnical hazards affecting foundations and earth structures during earthquakes. Although geosynthetic-encased stone columns (GESCs) have demonstrated promising performance in mitigating liquefaction, their behavior has primarily been investigated at the single-column level, while the seismic response of finite GESC groups remains insufficiently understood. This study evaluates the seismic performance of stone column (SC) and GESC groups arranged in square patterns using a three-dimensional coupled hydro-mechanical finite-element model developed in OpenSeesSP. A comprehensive parametric study was conducted to investigate the effects of column-group configuration (1 × 1, 3 × 3, 5 × 5, and 7 × 7), geosynthetic encasement thickness, stone column permeability, geosynthetic permeability, and column spacing under the 1940 El Centro earthquake excitation. The results show that GESC groups substantially improve liquefaction mitigation by accelerating pore-water pressure dissipation and reducing earthquake-induced ground deformation. Compared with untreated ground, GESC groups arranged in 3 × 3, 5 × 5, and 7 × 7 configurations reduce lateral ground displacement by up to 70%. Furthermore, increasing the group size from a single encased column (1 × 1) to a 7 × 7 GESC group decreases lateral deformation at the model by approximately 40%, highlighting the importance of column-group configuration in controlling seismic ground response. Overall, the proposed numerical framework provides practical guidance for optimizing GESC design and improving the seismic performance of liquefaction-prone ground.