液化地基上隔震结构群桩与土动力相互作用振动台模型试验研究

Earthquake responses of piles-soil dynamic interaction system for base-isolated structure system based on shaking table tests

开展了液化场地-桩-隔震层-上部结构动力相互作用体系的大型振动台模型试验,再现饱和砂土地基液化诱发的地基震陷震害,详细阐述了隔震结构群桩基础与地基的地震响应特征和饱和土体孔压发展规律。试验结果表明:隔震结构群桩基础的角桩桩身应变幅值明显高于中间桩,中间桩顶部应变幅值又明显高于角桩;隔震结构地基液化后上部结构摇摆和基础转动反应急剧增加,进而导致群桩基础桩顶弯矩急剧增加,使得桩身最大弯矩幅值由地基液化前的桩身中上部转移到地基液化后的桩顶位移,同时隔震结构下部桩顶弯矩幅值比桩身弯矩幅值也要大得多,充分说明在土-桩-隔震层-上部结构的动力相互作用下桩顶更易造成严重的地震破坏。

Due to the severe earthquake damage of ground structures induced by soil liquefaction,a shaking table test is designed and completed to simulate the seismic performance of the soil-piles-isolated layer-structure interaction system.The earthquake responses of the liquefiable soil foundation and pile group foundation are analyzed.According to the test results,the strain response amplitudes of the corner pile are greatly larger than those of the middle pile at the same depth except that at the top of pile.On the contrary,the strain response amplitude at the top of the middle pile is much larger than that of the corner pile.Further more,the bending moment at the top of pile increases quickly after the liquefaction of soil foundation,which is also greatly larger than that at somewhere else of the same pile.Compared with the seismic responses of pile under the non-isolated structures,the great rotational vibration of the base-isolated structures and the bearing of piles should be induced more severely due to the complicated soil-piles-isolated layer-structure dynamic interaction.