Considering the increasing applications of micropile systems in seismically active areas, a better understanding of their seismic performance and the key controlling factors is of high significance. This paper presents experimental investigations of the seismic performance of a small-scale physical model of micropiles under seismic ground motions. Shaking table tests were performed on a 4 × 4 group of vertical micropiles embedded in loose sand. Horizontal acceleration time histories recorded from the 1940 El Centro earthquake and 1995 Kobe earthquake were applied to the base of the soil container. The response of the physical model was monitored in terms of horizontal accelerations at different levels and bending moments induced in the micropiles. The experimental results indicate that in all shaking events, the magnitudes of horizontal accelerations on the soil surface and the pile cap were amplified with respect to the input motion. Bending moments were induced in the micropiles and peaked at the mid-depth. It was also found that inclining the micropiles led to improvement in their seismic performance, reducing both the acceleration response on soil surface and pile cap, and the induced bending moments in the micropiles. Finite element simulations of shaking table tests have been performed, and the results are in reasonable agreement with observations from the experiments.

中文翻译：

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1-g振动台研究微桩系统对地震激励的响应

考虑到微桩系统在地震活跃地区的日益增长的应用，更好地了解其抗震性能和关键控制因素具有重要意义。本文介绍了在地震地震动下微型桩的小型物理模型的抗震性能的实验研究。摇床测试是对嵌入松散沙子中的4×4组垂直微型桩进行的。将1940年El Centro地震和1995年神户地震记录的水平加速时间历史记录应用于土壤容器的底部。物理模型的响应通过不同水平的水平加速度和微桩中引起的弯矩来监控。实验结果表明，在所有震动事件中，相对于输入运动，在土壤表面和桩帽上的水平加速度的大小被放大了。弯矩在微桩中引起，并在中深度达到峰值。还发现倾斜微型桩可改善其抗震性能，同时减小土壤表面和桩帽的加速度响应以及微型桩中引起的弯矩。进行了振动台试验的有限元模拟，其结果与实验观察结果基本吻合。减少土壤表面和桩帽上的加速度响应以及微桩中引起的弯矩。进行了振动台试验的有限元模拟，结果与实验观察结果基本吻合。减少土壤表面和桩帽上的加速度响应以及微桩中引起的弯矩。进行了振动台试验的有限元模拟，其结果与实验观察结果基本吻合。