| 颗粒破碎条件下的胶结砂力学行为 |
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| 引用本文： | 李博,陈宇龙.颗粒破碎条件下的胶结砂力学行为[J].西南交通大学学报,2016,29(4):729-735. |
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| 作者姓名： | 李博 陈宇龙 |
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| 作者单位： | 贵州大学喀斯特环境与地质灾害防治教育部实验室;东京大学土木工程系 |
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| 基金项目： | 国家自然基金资助项目(41430318) |
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| 摘 要： | 为揭示胶结量对胶结砂的力学行为与颗粒破碎的影响,引入颗粒破碎的概念,采用颗粒流商业软件PFC对胶结砂力学行为进行了三维颗粒流数值模拟,对不同胶结量的试样进行了一系列的三轴压缩试验,并与实验结果进行对比.在此基础上,分析了数值模拟中胶结试样的微观力学响应.研究结果表明:颗粒流数值模拟能够有效地描述胶结砂的主要力学行为,相比无胶结的试件,胶结砂表现出更高的强度,应力-应变关系曲线呈应变软化型,体积应变为先剪缩后剪胀;胶结砂宏观力学响应(应力-应变关系和剪胀性)与其微观力学响应密切相关,在加载的初期,胶结点破坏率和破坏速率较低,在屈服点后迅速增长,峰值应力点后,胶结点破坏速率和胶结点破坏率趋于平缓;胶结量越小,胶结强度越低,胶结点破坏率和速率越高;胶结量越高,颗粒破碎的比例越高,体积膨胀量越大;胶结量分别为0和100%时,颗粒破碎的比例分别为1.13%和10.96%.胶结作用的存在促进了剪切带的孕育,与无胶结试样相比,胶结试样内部颗粒接触力链更粗、更集中.
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| 关 键 词： | 胶结砂 颗粒 破碎 胶结破坏 数值模拟 |
| 收稿时间： | 2015-06-11 |
Mechanical Behavior of Cemented Sand Considering Particle Breakage |
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| LI Bo;CHEN Yulong.Mechanical Behavior of Cemented Sand Considering Particle Breakage[J].Journal of Southwest Jiaotong University,2016,29(4):729-735. |
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| Authors: | LI Bo;CHEN Yulong |
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| Affiliation: | LI Bo;CHEN Yulong;Key Laboratory of Karst Environment and Geohazard Prevention,Ministry of Education,Guizhou University;Department of Civil Engineering,University of Tokyo; |
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| Abstract: | In order to study the effect of bonding proportion on behaviors of cemented sand combined with particle breakage effect, the conception of particle breakage was introduced and cemented sand behaviors were studied by numerical simulation with the built contact bond model in PFC3D. A series of triaxial compression tests on cemented sand of different bond proportions were carried out. Then, the simulated results were compared with the test results on artificially cemented sand from laboratory tests. The micromechanical responses were analyzed by numerical simulation. Results show that the discrete element method model is able to capture the main mechanical behaviors of cemented sand. Compared with uncemented sand, cemented sand has greater strength, and shows strain-softening in stress-strain curve and transition from compaction to shear-dilation in volumetric strain. The macromechanical responses of cemented sand (stress-strain relationship and dilatancy) are closely associated with the micromechanical responses. Bond breakage ratio and rate are low at the initial loading stage and then rapidly increase after yielding point. Bond breakage rate peaks at peak strength and deceases afterward, while the bond breakage ratio increases slowly and become stable. A sample with lower bond proportion and bond strength has higher bond breakage ratio and rate. High bond proportion leads to more broken particles and dilation in volume. When bond proportions are 0 and 100% respectively, particle breakage ratio increases from 1.13% to 10.96%. In contrast to uncemented sand, the bond develops the shear band, and larger and more concentrated contact force. |
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