纳米尺度下煤的力学性质及破坏机制研究

doi:10.13722/j.cnki.jrme.2019.0659

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摘要研究煤的微观力学性质及破坏机制，对于补充和解释煤的物理力学性质具有重要意义。通过纳米压痕试验得到了赵庄矿原煤煤样的力学性质，并对赵庄煤大分子基体模型进行纳米压痕分子模拟，将模拟结果与试验进行对比分析。试验结果表明，赵庄煤在静态和动态加载模式下的平均硬度分别为0.423和0.560 GPa；平均弹性模量分别为4.452和5.200 GPa。结合Weibull分布函数对试验数据进行统计分析，2种加载模式下硬度和弹性模量对应的Weibull模数均大于20。基于构建的赵庄煤大分子，实现了赵庄煤大分子基体模型的纳米压痕分子动力学模拟，从分子尺度揭示了煤体的破坏机制。通过Oliver-Pharr法和赫兹理论求出赵庄煤分子模拟下的硬度及弹性模量，与试验结果吻合较好。在模拟过程中系统的势能随着压深而逐渐增大，卸载阶段势能逐渐降低，但由于基体发生的破坏变形储存了部分能量，完全卸载后的势能要大于初始势能。随着压头的深入，煤大分子之间相互挤压，形成原子稠密区，失去原有的键结强度，形成损伤层。结合径向分布曲线和键角分布曲线发现，在煤基体破坏过程中，煤大分子间的有序度不断降低，煤大分子中的环状结构在抵抗破坏过程中起到重要作用。

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	孟筠青1
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	夏捃凯1
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	阚李浩1
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关键词 ：岩石力学, 纳米压痕, 煤大分子, Weibull分布, 分子动力学

Abstract：Coal micro mechanical properties and failure mechanisms are of key importance to supplement and explain the physical and mechanical properties of coal. Nanoindentation tests were carried out to obtain micro mechanical properties of Zhaozhuang coal，molecular dynamics simulation of the macromolecule matrix of Zhaozhuang coal was performed，and their results were compared with each other. The results show that the average hardnesses of Zhaozhuang coal in static and dynamic loading modes are respectively 0.423 and 0.560 GPa，and the average elastic moduli are 4.452 and 5.200 GPa，respectively. The Weibull distribution moduli corresponding to the elastic modulus and hardness of Zhaozhuang coal under the two loading modes are greater than 20. The failure mechanisms at the molecular scale were revealed through nanoindentation molecular dynamics simulations of Zhaozhuang coal macromolecule matrix. The hardness and elastic modulus of Zhaozhuang coal molecular simulation were obtained using Oliver-Pharr method and Hertz theory，which are approximately agreed with the tests. In the simulation process，the potential energy of the system increases while loading but decreases while unloading. The final potential energy is higher than the beginning because of the plastic deformation. When the indenter is embedded，the atomic dense area is formed due to mutual extrusion of coal macromolecules and further，the damaged layer occurs because of the loss of the original bond strength. The research on the structure of coal macromolecule matrix by using radial distribution function and bond angle distribution shows that in the process of coal matrix failure，the order degree of coal macromolecule decreases and the ring structure in coal macromolecule plays an important role in failure resisting.

Key words： rock mechanics')" href="#">

rock mechanics nanoindentation coal macromolecule Weibull distribution ')" href="#">molecular dynamics

引用本文:

孟筠青1，2，3，牛家兴1，2，夏捃凯1，2，阚李浩1，2. 纳米尺度下煤的力学性质及破坏机制研究[J]. 岩石力学与工程学报, 2020, 39(1): 84-92.
MENG Junqing1，2，3，NIU Jiaxing1，2，XIA Junkai1，2，KAN Lihao1，2. Study on mechanical properties and failure mechanisms of coal at the nanometer scale. , 2020, 39(1): 84-92.

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http://www.rockmech.org/CN/10.13722/j.cnki.jrme.2019.0659 或 http://www.rockmech.org/CN/Y2020/V39/I1/84

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