Numerical study to evaluate the effect of encased stone columns technique for liquefaction mitigation of sandy soil by PLAXIS 2D

Abstract Liquefaction of sandy soil under seismic loading is a serious hazard to infrastructure due to excessive ground deformation and bearing strength loss. Various ground improvement techniques have been attempted to address the issue, of which encased stone columns ( ESC ) have recently shown great promise. While stone columns ( SCs ) provide drainage and reinforcement, adding a geosynthetic encasement contributes lateral support and potentially seismic performance. This study employs 2D finite element modeling with PLAXIS 2D and the UBC3D-PLM model to predict the performance of ESC in liquefaction mitigation. It is validated with laboratory experiments and simulation of three cases: without SC , with SC , and with ESC . The performance of the three is compared based on the excess pore water pressure ratio ( r u ), excess pore water pressure ( EPP ), settlement, and effective stresses. The 1940 El Centro earthquake was utilized as input motion to simulate dynamic conditions. Parameters such as column spacing, diameter, permeability, and encasement stiffness are considered. The results indicate that ESCs improve the soil response significantly during seismic loading. ESCs decrease the EPP buildup to less than in other cases and lower ground settlement than SC due to encasement. Reducing spacing-to-diameter ( s/d ) values and higher permeability enhance drainage and induce faster pore pressure dissipation. ESCs also increase effective stress and aid in managing vertical and lateral deformations. Therefore, the results illustrate the performance of ESCs in improving ground stability and liquefaction resistance during earthquakes.