In this study,centrifuge model tests of vertical and batter pile groups in liquefied sand were conducted on a centrifuge shaking table.The dynamic p-y curves for these pile groups before and during sand liquefaction w...In this study,centrifuge model tests of vertical and batter pile groups in liquefied sand were conducted on a centrifuge shaking table.The dynamic p-y curves for these pile groups before and during sand liquefaction were obtained from calculations based on test data.The results confirm that liquefaction contributes to a reduction in the energy consumption of pile foundations,with the degradation effect being more pronounced for batter pile groups.At shallow depths,the difference in the backbone gradients of the p-y curves after liquefaction for vertical and batter pile groups indicates that the lateral stiffness of a batter pile group is greater than that of a vertical pile group.As shaking intensity increases,the lateral stiffness of a vertical pile group increases with depth during the late stage of sand liquefaction.However,the lateral stiffness of a batter pile group during liquefaction does not vary with depth.The results of this study provide a reference for the seismic design of vertical and batter pile groups in liquefied soil.展开更多
为了更好地研究地震作用下饱和砂土中群桩及土体动力响应特征,设计了饱和砂土液化场地2×2直群桩动力响应离心机振动台试验,获得承台、土体加速度以及孔压动力时程曲线。为了更深入地分析群桩及土体地震动力响应特征并满足对比研究...为了更好地研究地震作用下饱和砂土中群桩及土体动力响应特征,设计了饱和砂土液化场地2×2直群桩动力响应离心机振动台试验,获得承台、土体加速度以及孔压动力时程曲线。为了更深入地分析群桩及土体地震动力响应特征并满足对比研究的需要,在试验基础上,基于ABAQUS有限元软件平台,通过引入砂土液化大变形本构模型,采用有限元网格自适应调整技术克服大变形畸变问题,建立液化场地群桩基础静动耦合非线性相互作用的二维有限元模型进行数值模拟分析,并与试验结果进行对比验证。结果表明:在峰值加速度0.3 g El-Centro地震波工况下离心机振动台试验饱和砂土地基液化速度非常快,直群桩基础承台加速度相比较输入波明显缩小,0.3 g大震作用下地基浅层加速度显著衰减,地基液化区域由浅入深逐渐发育;饱和砂土地基超静孔隙水压力发展影响土体和桩基承台加速度响应,土体液化直接导致加速度数值减小;数值模拟加速度结果与试验的加速度动力响应特性略有区别,数值模拟加速度地基浅层出现先放大后缩小的规律,深层土与输入波形基本一致;数值模拟超静孔隙水压力与超静孔压比与试验基本一致,而模拟得到的承台位移结果相较于试验偏于保守。展开更多
基金Supported by:National Natural Science Foundation of China under Grant No.51778207the Project of Graduate Students′Innovative Ability Training of Hebei Province under Grant No.CXZZBS2019041the Natural Science Foundation of Hebei Province under Grant No.E2018202107。
文摘In this study,centrifuge model tests of vertical and batter pile groups in liquefied sand were conducted on a centrifuge shaking table.The dynamic p-y curves for these pile groups before and during sand liquefaction were obtained from calculations based on test data.The results confirm that liquefaction contributes to a reduction in the energy consumption of pile foundations,with the degradation effect being more pronounced for batter pile groups.At shallow depths,the difference in the backbone gradients of the p-y curves after liquefaction for vertical and batter pile groups indicates that the lateral stiffness of a batter pile group is greater than that of a vertical pile group.As shaking intensity increases,the lateral stiffness of a vertical pile group increases with depth during the late stage of sand liquefaction.However,the lateral stiffness of a batter pile group during liquefaction does not vary with depth.The results of this study provide a reference for the seismic design of vertical and batter pile groups in liquefied soil.
文摘为了更好地研究地震作用下饱和砂土中群桩及土体动力响应特征,设计了饱和砂土液化场地2×2直群桩动力响应离心机振动台试验,获得承台、土体加速度以及孔压动力时程曲线。为了更深入地分析群桩及土体地震动力响应特征并满足对比研究的需要,在试验基础上,基于ABAQUS有限元软件平台,通过引入砂土液化大变形本构模型,采用有限元网格自适应调整技术克服大变形畸变问题,建立液化场地群桩基础静动耦合非线性相互作用的二维有限元模型进行数值模拟分析,并与试验结果进行对比验证。结果表明:在峰值加速度0.3 g El-Centro地震波工况下离心机振动台试验饱和砂土地基液化速度非常快,直群桩基础承台加速度相比较输入波明显缩小,0.3 g大震作用下地基浅层加速度显著衰减,地基液化区域由浅入深逐渐发育;饱和砂土地基超静孔隙水压力发展影响土体和桩基承台加速度响应,土体液化直接导致加速度数值减小;数值模拟加速度结果与试验的加速度动力响应特性略有区别,数值模拟加速度地基浅层出现先放大后缩小的规律,深层土与输入波形基本一致;数值模拟超静孔隙水压力与超静孔压比与试验基本一致,而模拟得到的承台位移结果相较于试验偏于保守。
