地震作用下含倾斜软弱夹层边坡内群桩的弯曲变形研究

 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。

Bending deformation of pile group in the slope with intercalated weak layer under seismic excitations

The centrifugal shaking table test with the centrifugal acceleration of 50 g was carried out to investigate the bending moments and deformation modes of the pile group installed slope with intercalated weak layer and to investigate the effect of the inner deformation of slope and the inertia force of superstructure on the pile group foundation. The results showed that the bending deformation of the pile group foundation was controlled by the inertia force of the superstructure under the seismic excitations，and the range is limited around the pile top and take up 26%–28% of overall length of the piles. The modes of bending deformation of the pile group foundation were classified as the uniform type and the non-uniform type，the types with and without the inflection point，the parallel and non-parallel types. The effect of intercalated weak layer on the amplification coefficients of acceleration within the slope is related to the peak values of input accelerations and the amplification coefficients of the weak intercalated layer increased nonlinearly with the increasing of the peak values of input acceleration. Besides，there are obvious differences in the dynamic responses of superstructure and ground surface of the slope，and the differences were increased nonlinearly with the increasing of the peak seismic acceleration and were multiple increased when the input acceleration peak is equal or greater than 0.25 g.