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针对含软弱夹层边坡场地中的群桩基础,设计并完成50 g超重力离心振动台模型试验,探讨群桩结构的弯矩分布特性和弯曲变形模式,以及场地内部变形和上部结构惯性力对群桩基础的影响。试验结果表明:地震作用下,上部结构的惯性力控制了群桩的弯曲变形,影响范围从桩顶向下为桩长的26%~28%;群桩的弯曲变形形态从整体协调变形角度可分为一致型和非一致型、有拐点型和无拐点型、平行型和非平行型;场地中倾斜软弱夹层对场地内加速度放大系数的影响与输入加速度峰值有关,随着输入加速度峰值的增大,该软弱夹层内部的放大系数呈非线性增长;此外,该上部结构与场地表面的动力响应存在明显差异,且其会随地震强度增加呈非线性扩大趋势,当输入加速度峰值≥0.25 g时会出现成倍突增现象。
Aiming at the group pile foundation in the site with weak interlayer slope, a 50 g centrifugal model test was designed to investigate the distribution characteristics of bending moment and bending deformation of the pile group structure, as well as the internal deformation and the inertial force of the superstructure Influence of pile foundation. The results show that under the action of earthquake, the inertial force of the superstructure controls the bending deformation of pile group, and the influence range is 26% -28% of the pile length downward from the top of the pile. The bending deformation of pile group can be adjusted from the overall coordination Which is divided into two types: uniform type and non-uniform type, inflection point type and non-inflection type, parallel type and non-parallel type. The influence of inclined soft interlayer on acceleration amplification factor in site is related to the peak of input acceleration. In addition, the dynamic response of the superstructure to the surface of the site is obviously different, and it increases nonlinearly with the increase of earthquake intensity. When the input acceleration peak is greater than or equal to 0.25 g There will be doubled phenomenon.