Stone column is one of the prevailing liquefaction mitigation techniques to densify the surrounding soil, expedite the drainage and bring the possible shear reinforcement effect. The mitigation mechanisms of liquefaction triggering and the associated deformation of the improved ground have not been well explored yet, which hinders the development of robust design in engineering practices. Three centrifuge model tests, including a loose sand model, a dense sand model and a dense sand model with stone columns were conducted to explore the individual effect of densification and drainage caused by stone columns on seismic responses of a level silty sand ground, including the excess pore water pressure, acceleration and ground settlement, etc. The densification effect increases the dilatancy of the surrounding soil and hinders the generation of excess pore water pressure during shaking, thus significantly reduces the liquefaction potential and post-shaking settlement as well. However, it amplifies the upward propagating ground motion considerably. The drainage effect in a densified ground with SCs mainly takes place after shaking, and it accelerates the dissipation rate about 5–10 times that of a densified ground without SCs, which helps to quickly restore the ground stiffness and reduce the deformation to some extent. The contributions from the two effects to the post-shaking ground settlement were also observed and discussed. The present study provides insights on liquefaction mitigation mechanisms of the stone column-improved ground and valuable benchmark tests for further analysis.

石柱是一种流行的液化缓解技术，可以使周围土壤致密，加速排水并带来可能的抗剪加固效果。液化触发的缓解机制和改良地面的相关变形尚未得到很好的探索，这阻碍了工程实践中稳健设计的发展。进行了松散砂模型、密砂模型和带石柱的密砂模型三个离心模型试验，探讨了石柱致密化和排水对水平粉砂质砂地地震响应的个别影响，包括超孔隙水压力、加速度和地面沉降等。致密化效应增加了周围土壤的剪胀性，阻碍了振动过程中超孔隙水压力的产生，从而显着降低了液化潜力和振动后沉降。然而，它大大放大了向上传播的地面运动。含SCs的致密地基的排水作用主要发生在震动后，其耗散速度比无SCs的致密地层加快5～10倍左右，有助于快速恢复地基刚度，并在一定程度上减少变形。还观察和讨论了两种效应对震动后地面沉降的贡献。本研究为石柱改良地面的液化减缓机制提供了见解，并为进一步分析提供了有价值的基准测试。