基于离散元法的沥青混合料真空压实机理仿真研究

发布时间：2018-06-06 21:26

本文选题：沥青混合料 + 离散元　；参考：《长安大学》2017年硕士论文

【摘要】：为了从微观角度对真空压实机理进行探究,本文根据离散元方法的基本原理和离散元应用程序PFC3D的相关特点,分析沥青混合料的组成结构和性质,分别确立了沥青混合料中各相的建模或表达方法,其中重点分析了沥青混合料中封闭气泡的建模原理和在应用程序PFC3D中的具体实现算法,从而建立了含封闭气泡的沥青混合料离散元模型。基于该松散沥青混合料离散元模型,模拟了混合料压实过程,监测了压实过程中混合料整体的变化和内部封闭气泡的力学特性,数值模拟结果与实际情况相符,证明了沥青混合料压实过程数值模拟的可行性和该离散元模型的准确性。基于以上离散元模型,本文分别模拟了常规和真空条件下的沥青混合料压实过程,并根据实验结果对真空压实模型进行了修正,得到了较合理的结果。模拟结果显示:同样的外荷载下,真空压实比常规压实试件沉降量更大;真空压实相比常规压实,所得压实试件内封闭气泡体积被压缩更小,试件总空隙率更低;真空环境除了有利于降低沥青混合料内“气体弹簧”效应外,还对沥青胶浆的性质或者骨料-沥青界面的质量有影响。为了充分比较常规压实和真空压实的区别,本文又对两种条件下压实所得试件进行了单轴压缩试验模拟。模拟结果显示:常规压实试件抗压强度为1.68MPa,对应的轴向应变为0.0353;真空压实试件抗压强度为1.72MPa,对应的轴向应变为0.0311,真空压实试件相比常规压实试件抗压强度更高,相应的应变量更小。
[Abstract]:In order to explore the mechanism of vacuum compaction from the micro point of view, based on the basic principle of the discrete element method and the related characteristics of the discrete element application program PFC3D, this paper analyzes the composition and properties of the asphalt mixture, establishes the modeling or expression method of each phase in the asphalt mixture, and focuses on the analysis of the sealing in the asphalt mixture. The modeling principle of bubble and the concrete realization algorithm in application program PFC3D have been established, and the discrete element model of asphalt mixture with closed bubbles is established. Based on the discrete element model of the loose asphalt mixture, the compacting process of the mixture is simulated. The change of the mixture and the mechanical properties of the internal closed bubble are monitored. The value simulation results agree with the actual situation, which proves the feasibility of the numerical simulation of the asphalt mixture compaction process and the accuracy of the discrete element model. Based on the above discrete element model, the compaction process of the asphalt mixture under the conventional and vacuum conditions is simulated, and the vacuum compaction model is amended according to the actual results. The results show that the vacuum compaction is smaller than the conventional compaction, and the total void fraction of the specimen is lower than the conventional compaction, and the vacuum environment is beneficial to reduce the "gas spring" effect in the asphalt mixture. In addition, the properties of asphalt mortar and the quality of aggregate bitumen interface are also affected. In order to compare the difference between the conventional compaction and the vacuum compaction, a single axial compression test is carried out on the compacted specimens under two conditions. The simulation results show that the compressive strength of the conventional compacted specimen is 1.68MPa and the corresponding axial strain is 0.0353. The compressive strength of the vacuum compacted specimen is 1.72MPa and the corresponding axial strain is 0.0311. The compressive strength of the vacuum compacted specimen is higher than that of the conventional compacted specimen, and the corresponding strain is smaller.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U414

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