地震作用下不同厚度饱和砂土中直群桩结构动力响应试验研究

Experimental Study on the Dynamic Response of Vertical Pile-Group Structure in Saturated Sand with Different Thicknesses under Earthquake Action

摘要:

基于振动台试验，设计制作2×2直群桩结构相似模型，通过输入一定峰值加速度的迁安波，对非液化砂土、300 mm厚饱和砂土和380 mm厚饱和砂土中群桩承台横向动力响应特性展开研究。研究结果表明：在迁安波输入下，非液化砂土中群桩承台加速度和位移时程与台面输入时程相比，其波形变化规律与峰值大小没有明显差异；而对于两种不同厚度饱和砂土中承台加速度放大较多，承台位移峰值较台面位移峰值相差不大。在300 mm饱和砂土中群桩承台加速度峰值较台面输入放大了约1.35倍，在380 mm饱和砂土中承台加速度峰值放大了1.42倍，说明在相同输入条件下，较厚的饱和砂土层在发生液化后群桩承台的动力响应更加显著。

Abstract:

Based on the shaking table test, in this study, we designed a similar model of a 2×2 vertical pile-group structure. By inputting the Qian'an seismic wave with a certain peak acceleration, the lateral dynamic response characteristics of a vertical pile-group cap in non-liquefied, saturated sand with different thicknesses of 300 mm and 380 mm were studied by the shaking table test. The results showed that under the Qian'an wave input, the acceleration and displacement time histories of the pile-group cap in non-liquefied sand were not significantly different from those at the platform; for the two sand thicknesses, the acceleration amplification of the pile-group cap in the saturated sands was enlarged, but the peak displacements of the pile-group cap were not much different from those at the platform. In 300 mm and 380 mm saturated sands, the peak acceleration of the pile-group cap was amplified by 1.35 times and 1.42 times, respectively, compared with that of the platform input, which shows that under the same input condition, the dynamic response of the pile-group cap was more remarkable in the thicker saturated sand after the liquefaction.