基于离散元法均匀性对沥青混合料力学性能影响研究

发布时间：2018-05-19 22:14

本文选题：沥青混合料 + CT技术　；参考：《浙江大学》2015年硕士论文

【摘要】：沥青混合料是一种复杂的强粘结颗粒体系,具有明显的非线性力学特征。较连续介质力学法而言,离散单元法考虑到了沥青混合料的颗粒体系与非线性特征,同时可以量化沥青混合料受载过程中的内部应力,更适合模拟沥青混合料的力学行为。当前大多数问题已经可以通过二维离散元模型来解决,但二维离散元法难以模拟沥青混合料复杂的内部结构,也无法真实地反应其粘弹性性质。本文基于CT技术和数字图像处理手段,采用三维离散元软件PFC3D对沥青混合料高低温性能及抗剪性能进行数值模拟研究,同时结合沥青混合料整体均匀性指标,探究沥青混合料细微观结构对其力学性能的影响效应。本文基于CT技术和数字图像处理手段,介绍并实现了沥青混合料三维离散元重构及数值模拟过程。其中集料采用实际边界,并赋予接触粘结模型及Burgers粘弹性模型,分别模拟了沥青混合料低温劈裂试验、高温单轴压缩试验、单轴贯入试验以及单轴静态蠕变试验,同时结合沥青混合料整体均匀性指标,分析了沥青混合料细微观结构特征与宏观力学性能之间的关系,并通过室内试验加以验证。然后基于室内试验结果,对比分析了三维离散元模拟与二维离散元模拟的不同,并对其各自的适用性进行了分析。本文最后分析了三维离散元模拟过程中几何模型、模型参数以及荷载边界条件对数值模拟结果的影响。研究结果表明：通过CT技术及数字图像处理手段可以方便地获取沥青混合料的内部结构信息,三维离散单元法可以用于模拟沥青混合料的宏观力学试验,结合沥青混合料整体均匀性指标,可以建立沥青混合料细微观结构与宏观力学性能变异性之间的联系。沥青混合料的整体均匀性与其高低温力学性能的变异性具有正相关性。相比于二维离散元法,三维离散元法更适合对沥青混合料的力学性能进行研究。在三维离散元建模过程中,几何模型、模型参数以及荷载边界条件均会对模拟结果有不同程度的影响。
[Abstract]:Asphalt mixture is a kind of complex strongly bonded particle system with obvious nonlinear mechanical characteristics. Compared with the continuum mechanics method, the discrete element method takes into account the particle system and nonlinear characteristics of asphalt mixture, and can quantify the internal stress in the course of asphalt mixture loading, so it is more suitable to simulate the mechanical behavior of asphalt mixture. Most of the problems can be solved by two-dimensional discrete element model, but the two-dimensional discrete element method can not simulate the complex internal structure of asphalt mixture, nor can it truly reflect the viscoelastic properties of asphalt mixture. Based on CT technology and digital image processing, this paper uses 3D discrete element software PFC3D to simulate the high and low temperature performance and shear resistance of asphalt mixture, and combines the whole uniformity index of asphalt mixture. To explore the effect of fine microstructure of asphalt mixture on its mechanical properties. Based on CT technology and digital image processing, the reconstruction and numerical simulation process of asphalt mixture 3D discrete element are introduced and realized in this paper. The aggregate adopts the actual boundary, and the contact bond model and Burgers viscoelastic model are given to simulate the bituminous mixture at low temperature splitting test, high temperature uniaxial compression test, uniaxial penetration test and uniaxial static creep test, respectively. At the same time, the relationship between fine microstructure and macroscopic mechanical properties of asphalt mixture is analyzed, which is verified by laboratory tests. Then, based on the results of laboratory tests, the differences between three-dimensional and two-dimensional discrete-time element simulations are compared and their applicability is analyzed. Finally, the effects of geometric model, model parameters and load boundary conditions on the numerical simulation results are analyzed. The results show that the internal structure information of asphalt mixture can be easily obtained by means of CT and digital image processing, and the three-dimensional discrete element method can be used to simulate the macroscopic mechanical test of asphalt mixture. The relationship between the fine microstructure of asphalt mixture and the variation of macroscopic mechanical properties can be established by combining the overall uniformity index of asphalt mixture. The overall uniformity of asphalt mixture is positively correlated with the variability of its mechanical properties at high and low temperatures. Compared with the two-dimensional discrete element method, the three-dimensional discrete element method is more suitable to study the mechanical properties of asphalt mixture. In the process of 3D discrete element modeling, geometric model, model parameters and load boundary conditions all have different effects on the simulation results.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U414

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