Numerical assessment of the influence of stone columns on liquefaction-induced seismic effects in RC structures

The cyclic shear stress induced in loosesaturated sandy soil owing to seismic loading may trigger liquefactionphenomena. Seismic-induced liquefaction can cause significant damage to thesub-structure and the super-structure resting on the soil stratum. Severalstudies have highlighted the effectiveness of stone columns in mitigatingliquefaction. However, their influence on the reinforced concrete (RC) structural demands during earthquakes remains underexplored. This studypresents a comprehensive three-dimensional finite-element investigation of theseismic responses of a RC superstructure founded on a shallow footing, withstone columns installed to mitigate soil liquefaction. Numerical analyses werecarried out on four types of soil-foundation-superstructure systems: model witha rigid-base, a model without liquefaction effects, a model with liquefactioneffects, and a model with stone column mitigation system. Non-lineartime-history analysis (NLTHA) performed to assess the effects of the peakground acceleration and excitation frequency. The numerical findings werevalidated against data from centrifuge and shake table tests. The results wereestimated and presented in terms of the settlement of soil and foundation, excess pore pressure, acceleration response, structural responses. Incorporating stone columns in liquefiable soils reduced inter-storey drift by 49% and pore pressure by 55%, enhancing overall performance.