Abstract Observations from previous strong earthquakes reported severe damage of piles installed in different soils, particularly liquefiable saturated sand deposits. This paper examines the seismic performance of pile group-structure system in liquefiable and non-liquefiable sand deposits using large-scale shaking table tests, and discusses the possible failure modes of pile foundation in liquefied site and non-liquefied site. Accelerations and strains of piles, and lateral displacements and accelerations of model soil were recorded. The measured piles’ accelerations and strains were used to calculate their bending moment profiles during the shaking, while the soil dynamic shear strain – shear stress curves were obtained using measured soil accelerations. In addition, characteristics of dynamic responses for liquefied and non-liquefied sites were evaluated by comparing trends of acceleration and lateral displacements of model soil. Furthermore, the failure mode for pile foundations in liquefiable and non-liquefiable site were elucidated from the observed responses of the structure-pile foundation. It was found that (1) the stiffness of liquefied site degraded more significantly (compared to non-liquefies site) due to increase in pore water pressure, but the non-liquefied site experienced higher amplification of acceleration; (2) large lateral spreading did not occur in the liquefiable site experiment due to the horizontal surface of the underlying stable (non-liquefied) soil; (3) profiles of pile bending moment differed for liquefied and non-liquefied sites for the same excitation, which impacted the permanent deformation of the piles. The test results in this study can be used to validate related numerical models.

中文翻译：

---

大型振动台试验研究可液化和不可液化土中桩群-结构体系的抗震性能

摘要 以往强震的观测报告称，安装在不同土壤中的桩严重损坏，尤其是可液化的饱和砂沉积物。本文通过大型振动台试验，检验了可液化和不可液化砂土中桩群结构体系的抗震性能，并讨论了液化场地和非液化场地桩基可能的破坏模式。记录桩的加速度和应变，以及模型土的横向位移和加速度。测量桩的加速度和应变用于计算其在振动过程中的弯矩剖面，而土壤动态剪应变-剪应力曲线则使用测量的土壤加速度获得。此外，通过比较模型土的加速度和横向位移的趋势，评估了液化和非液化场地的动力响应特性。此外，通过观察到的结构桩基础的响应，阐明了可液化和不可液化场地中桩基的破坏模式。发现（1）由于孔隙水压力的增加，液化站点的刚度下降更显着（与非液化站点相比），但非液化站点的加速度放大率更高；(2) 可液化场地试验由于下伏稳定（非液化）土的水平面，未发生大的横向扩展；(3) 相同激励下，液化和非液化场地的桩弯矩分布不同，从而影响桩的永久变形。本研究的试验结果可用于验证相关数值模型。