| 饱和砂土自由场地地震液化的离散元模拟 |
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| 引用本文： | 史旦达,王飞.饱和砂土自由场地地震液化的离散元模拟[J].上海海事大学学报,2017,38(3):96-102. |
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| 作者姓名： | 史旦达 王飞 |
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| 作者单位： | 上海海事大学海洋科学与工程学院,华东建筑设计研究总院 |
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| 基金项目： | 国家自然科学基金（41772273，50909057）；上海市教育委员会科研创新项目（15ZZ081）；上海市软科学研究重点项目（16692105400） |
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| 摘 要： | 为研究饱和砂土自由场地的地震液化过程,基于颗粒离散元与计算流体动力学耦合方法,在PFC3D程序中通过二次开发实现对自由场地基底不规则地震波的输入,研究在实测Kobe地震波激励下该液化过程的宏细观力学响应,并与已有的福建中细砂离心机模型试验结果进行对比。数值模拟结果表明:试样发生液化的时刻对应于基底地震加速度峰值时刻,浅部土层先于深部土层发生液化,超静孔隙水压力的消散是从深部土层逐渐向浅部土层发展的;伴随液化过程,各深度土层的有效应力路径均从初始应力状态向应力空间的原点移动;数值试验呈现出的上述规律均与实际砂土离心机模型试验呈现出的规律保持一致。数值试样宏观的液化特征在微观机理上可由流体对颗粒的归一化拖曳力、局部孔隙比、平均配位数、颗粒位移的变化规律来相应表征。
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| 关 键 词： | 饱和砂土 自由场地 地震荷载 液化 离散元模拟 |
| 收稿时间： | 2016/6/19 0:00:00 |
| 修稿时间： | 2017/5/31 0:00:00 |
Discrete element simulation on seismic liquefaction of saturated free field sand deposits |
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| Institution: | School of Ocean Science and Engineering, Shanghai Maritime University |
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| Abstract: | In order to research the seismic liquefaction of saturated free field sand deposits, using the coupled method of the particle discrete element method and computational fluid dynamics, both macro and micro mechanical responses of the liquefaction are explored subjected to the real Kobe earthquake wave excitation, where the input of irregular seismic waves on free field base is realized by self developed procedures in PFC3D. The numerical results are compared with the centrifugal model test results on Fujian sand, which is a uniformly graded medium to fine sand. It is found that the exact instant for sample liquefaction corresponds to the peak time of the base seismic acceleration. Liquefaction happens in shallow sand layers prior to deep sand layers, whilst the excess pore water pressure dissipates earlier in deep layers than in shallow layers. During liquefaction, the effective stress path of each sand layer moves from the initial stress condition to the coordinate origin in the stress space. The above laws obtained by numerical tests are consistent with the laws obtained by the real sand centrifugal model test. The macroscopic liquefaction behaviors are correspondingly characterized by the normalized fluid drag force on particles, the porosity, the average coordination number and the particle displacement in the micro mechanism. |
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| Keywords: | saturated sand free field earthquake loading liquefaction discrete element simulation |
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