【摘要】 为研究可液化砂土地基中桩基体系在地震力作用下的动力特性,进行室内振动台天然地基、3D、3.5D、4D桩间距桩基加固地基四种工况模型试验。通过布设传感器对各工况下特定深度的初始有效应力、振动过程中超静孔隙水压力时程、沉降时程进行测定,对桩基加固地基振动前后竖向承载力进行分析。结果表明,桩基加固后的地基土发生液化滞后于天然地基,且桩间距为3D、3.5D的加固地基提高抗液化强度较明显。随桩间距的加大,提高程度会减弱;据不同工况振动过程中发生的最大沉降量,3D桩间距加固的桩基竖向动承载力较高;模拟地震力振动达稳定后桩基的竖向承载力均高于振动前同工况竖向承载力。试验分析可对饱和砂土在地震力作用下PSSI效应进一步理解,为桩基优化设计提供参考。更多还原

【Abstract】 In order to study dynamic characteristics of a pile foundation with liquefiable sandy soil under seismic loading,the four working conditions were studied including natural foundation,pile foundations with 3D,3.5D and 4D(D is the pile diameter) pile spaces by means of indoor shaking table model test.Initial effective stresses,time histories of excess pore water pressure and time histories of settlement during vibrations were determined with sensors.At the same time,the vertical bearing capacities of the pile reinforced foundations after vibrations were compared with those before vibrations.The test results showed that the liquefaction of soil for pile reinforced foundations delays compared with that of the natural foundation,and the pile foundations with 3D and 3.5D can more significantly improve liquefaction resistance;the vertical dynamic bearing capacity of the pile foundation with 3D is higher according to the largest settlement during vibration;all the vertical bearing capacities of pile foundations become larger after vibration.Based on the test,the pilesoil-structure dynamic interaction was understood more deeply during liquefaction of soil.The results provided a reference for optimal design of pile foundations.更多还原