Comparison of liquefaction behavior of granular material under SH- and Love-wave strain conditions by 3D DEM
Comparison of liquefaction behavior of granular material under SH- and Love-wave strain conditions by 3D DEM
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DOI：
10.1016/j.sandf.2021.06.013
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发表时间：
2021-07
影响因子：
3.7
通讯作者：
M. Jiang;Akiyoshi Kamura;M. Kazama
中科院分区：
文献类型：
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作者：
M. Jiang;Akiyoshi Kamura;M. Kazama
在研究与地震荷载条件相关的液化行为时，通常假设液化是由于横波向上传播而发生的，尽管有证据表明，水平传播的表面波可能导致或加剧液化损伤。本文基于三维离散元法，对颗粒材料在Love-wave应变条件下的液化行为进行了一系列数值试验研究。在宏观和微观尺度上讨论了颗粒填料在水平极化剪切- (SH-)和Love-wave应变条件下的响应。模拟结果表明，在宏观尺度上，Love-wave应变条件下的有效应力减小比SH-wave应变条件下的有效应力减小比增加得更快。基于能量的概念，可以认为Love-wave应变条件下的颗粒材料比SH-wave应变条件下的颗粒材料更容易液化。微尺度分析表明，在Love-wave应变条件下，主力链的主导方向发生空间旋转。此外，这里的重点放在配位数上，配位数表示每个粒子的平均接触数。SH-和Love-wave应变条件下颗粒填料骨架结构降解速度的差异可能在配位数减小到4左右的临界值后才会出现。当配位数接近3时，颗粒填料变得不稳定并很快液化。本文讨论了最小平均有效应力。
In the study of liquefaction behavior associated with seismic loading conditions, it is often assumed that liquefaction occurs owing to the upward propagation of shear waves, despite evidence that liquefaction damage may result from or be aggravated by horizontally propagating surface waves. In this study, a series of numerical tests, based on the three-dimensional discrete element method, is performed to examine the liquefaction behavior of granular materials under Love-wave strain conditions. The response of granular packings under horizontally polarized shear- (SH-) and Love-wave strain conditions is discussed at both macro- and microscales. The simulation results indicate that, at the macroscale, the effective stress reduction ratio increases more rapidly under Love-wave strain conditions than under SH-wave strain conditions. Based on the concept of energy, the granular materials under Love-wave strain conditions can be considered more vulnerable to liquefaction than those under SH-wave strain conditions. Microscale analysis indicates the spatial rotation of the dominant direction of backbone force-chains under Love-wave strain conditions. In addition, focus here is placed on the coordination number, which represents the average contact number per particle. The difference in the degradation speed of the skeleton structure of the granular packings between the SH- and Love-wave strain conditions may not appear until the coordination number has decreased to a critical value of around 4. After the coordination number has approached approximately 3, the granular packings become unstable and soon liquefy. The minimum mean effective stress is discussed herein.