| 控制应力路径散体材料真三轴试验强度特征的离散元模拟与细观机制分析 |
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| 引用本文： | 张 铎,刘 洋,吴顺川.控制应力路径散体材料真三轴试验强度特征的离散元模拟与细观机制分析[J].岩土力学,2016,37(Z1):509-520. |
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| 作者姓名： | 张 铎 刘 洋 吴顺川 |
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| 作者单位： | 1. 北京科技大学 土木与环境工程学院，北京 100083；2. 北京科技大学 金属矿山高效开采与安全教育部重点实验室，北京 100083 |
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| 基金项目： | 国家自然科学基金（No. 51178044）；北京市高校青年英才资助项目（No. YETP0340）；北京市优秀人才培养计划（No. 2013D009006000005）。 |
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| 摘 要： | 通过一系列真三轴离散元数值试验，模拟了不同应力路径下的等b试验中散体材料的强度特征。根据模拟结果详细地分析了三维应力条件下中主应力和应力路径对散体材料峰值强度的影响，研究了峰值摩擦角、峰值应力比的变化规律，并根据真应力的概念和组构张量的演化结果分析了散体材料的强度成因。研究表明，在不同类型的数值试验中峰值偏应力随b参数的变化规律不同，但采用初始围压归一化后的应力-应变曲线规律一致。峰值强度线的斜率只与b值有关而与应力路径无关，且随着b值的增加，峰值应力比qf /pf逐渐减小，数值模拟结果与室内试验结果吻合较好；随着应变的发展，数值试样的组构也随之发生变化，产生了明显的应力诱发各向异性；散体的强度为颗粒摩擦及材料各向异性共同作用的结果；理论上,组构比-应力比坐标系中破坏点位置仅取决于颗粒摩擦角 ，而数值模拟结果与理论值的差异源于颗粒间咬合和滚动摩擦的影响，其影响与颗粒表面摩擦系数有关，也受空间应力状态的影响。
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| 关 键 词： | 散体强度 数值模拟 离散元 真三轴试验 组构 |
| 收稿时间： | 2015-12-07 |
Simulation of strength characteristics of granular materials in true triaxial test for different stress paths and its mesoscopic mechanism analysis |
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| ZHANG Duo,LIU Yang,WU Shun-chuan.Simulation of strength characteristics of granular materials in true triaxial test for different stress paths and its mesoscopic mechanism analysis[J].Rock and Soil Mechanics,2016,37(Z1):509-520. |
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| Authors: | ZHANG Duo LIU Yang WU Shun-chuan |
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| Institution: | 1. Department of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China; 2. State Key Laboratory of High Efficient Mining and Safety of Metal Mines of Ministry of Education, University of Science and Technology Beijing, Beijing 100083, China |
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| Abstract: | A series of numerical simulation of constant b cubic tests are conducted using discrete element method to study the strength characteristics of granular materials under different stress paths. The influences of intermediate principal stress and stress path on the peak strength of granular materials are analyzed in 3-dimensional stress state based on the simulation numerical results. The variation of peak friction angle and peak stress ratio is also studied. Contributions to strength of granular materials are analyzed based on the true stress concept and the development of fabric tensor. Research results show that the variations of peak deviatoric stress with Bishop parameter are different in different type cubic tests; however, the stress-strain curves normalized by the initial confining stress are identical. The slope of peak strength line independent of stress path is only related to parameter b; and the peak stress ratio qf /pf decreases with an increase of b. Simulation results are in agreement with laboratory observations. Meanwhile, stress-induced fabric anisotropy is developed with the increasing strain. The strength of granular materials is the joint action of friction of particles and anisotropic fabric induced by the applied stress. Theoretically, the location of failure point in fabric ratio-stress ratio coordinate system is only decided by the particle apparent friction angle. The deviation between numerical simulation and theoretical analysis is origin from the effect of interlocking and rolling friction between particles and this influence is related to both particle friction coefficient and stress state. |
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| Keywords: | strength of granular materials numerical simulation discrete elements true triaxial test fabrics |
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