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进行液化地基–群桩–超高层建筑相互作用体系的振动台试验,再现饱和砂土地基液化诱发的结构体系侧向大变形的震害现象。通过试验,研究相互作用体系下地基液化、体系侧向大变形前后群桩基础的动力响应,对地基超孔隙水压力、群桩体系的基频、阻尼比、桩身应变、桩底接触压力和桩顶位移进行计算和分析。得到的规律主要有:群桩内外超孔隙水压力变化过程存在差异;随着激励峰值的提高,砂土层达到液化条件,群桩体系的频率降低、阻尼比增大;桩基的动力响应与地震波加速度峰值和频谱特性均有关;桩身应变变化量峰值沿桩身向上逐渐增大,桩顶裂缝多;不同地震波激励下,桩顶位移响应规律差异较大;承台两端角桩在地震波激励过程中表现出明显的一拉一压现象,揭示了结构体系大变形的根本原因。提出:提高群桩的抗压拔性能、改善地基的液化条件可提升超高层建筑–群桩体系的抗震能力。研究结果对超高层建筑–群桩体系抗震研究及防灾减灾具有重要意义。
Shaking table test of the interaction system of liquefied ground-pile group-super high-rise building is carried out to reproduce the seismic damage phenomenon of lateral deformation of structural system induced by liquefaction of saturated sand foundation. Through the experiment, the dynamic response of pile foundation under liquefaction of foundation and lateral deformation of system before and after deformation was investigated. The influence of pore water pressure, pile foundation pressure, damping ratio, pile body strain, bottom contact pressure and Pile top displacement calculation and analysis. The main regularities are as follows: the variation process of the excess pore water pressure inside and outside the pile group is different; with the stimulation peak increasing, the sand layer reaches the liquefaction condition, the frequency of pile group system decreases, the damping ratio increases; The peak acceleration of seismic wave and the spectral characteristics are related to each other; the peak value of strain change of pile increases gradually upward along the pile body, and there are many cracks on pile top; under different seismic waves, the displacement responses of pile top differ greatly; In the course of motivation, the phenomenon of unilateralism and tension was clearly shown, which revealed the fundamental reason for the great structural deformation. It is put forward that improving the anti-pressure performance of pile group and improving the liquefaction condition of foundation can improve the anti-seismic capacity of super high-rise building-group pile system. The research results are of great significance to the research on the aseismic behavior of super high-rise building-group pile system and disaster prevention and mitigation.