基于DEM的沥青混合料低温断裂特性的宏细观分析

发布时间：2018-10-10 20:34

【摘要】：沥青混合料作为一种多相复合材料,其低温断裂特性很大程度上受材料细观结构的影响,而这些因素难以通过室内试验手段体现,且常规的室内试验过程复杂、工作量大。因此,从宏细观相结合的角度采用虚拟试验方法研究沥青混合料低温断裂行为具有现实意义。本论文开展了如下工作:(1)通过分析试验参数,确定SCB室内试验加载方式,借此从断裂韧度、峰值荷载对应时间、裂缝长度的角度分析不同断裂加载模式和不同温度下沥青混合料宏观断裂特性,也为后文数值模拟结果提供对比依据;(2)构建了沥青混合料DEM数值模型,其主要包括:能够反映细观结构特性的物理模型和一种新型细观接触本构。该接触本构在不同加载条件下使用相同的数学结构,从而提供更好的模拟精度;(3)基于FISH语言编写代码,虚拟地再现SCB试验的加载条件,并导入前述沥青混合料数字模型和通过室内试验标定的细观参数,形成沥青混合料DEM虚拟试验方法,并验证虚拟试验方法的可靠性;(4)借助上述开发的虚拟试验方法,通过变换孔隙率、孔隙大小、孔隙分布、集料朝向角度、集料扁平率、集料含量、集料分布等,研究孔隙、集料几何特性和分布等沥青混合料细观结构对其断裂性能和裂缝萌生、发展规律的影响;(5)以接触力网为研究对象,分析沥青混合料集料结构特性;借助正交试验方法,分析不同组分对砂浆性能的影响规律。进而对沥青混合料组成进行优化,并通过常规室内试验予以验证。
[Abstract]:As a kind of multiphase composite material, the fracture characteristics of asphalt mixture at low temperature are largely affected by the meso-structure of the material, and these factors are difficult to be reflected by indoor test means, and the routine indoor test process is complicated and the workload is heavy. Therefore, it is of practical significance to study the low temperature fracture behavior of asphalt mixture by using virtual test method from the angle of macro-meso-view. The main work of this paper is as follows: (1) by analyzing the test parameters, the loading mode of SCB indoor test is determined, and the corresponding time of fracture toughness and peak load is obtained. The angle of crack length analyzes the macroscopic fracture characteristics of asphalt mixture under different fracture loading modes and different temperatures, which also provides a comparative basis for the later numerical simulation results. (2) the DEM numerical model of asphalt mixture is constructed. It mainly includes: a physical model which can reflect the characteristics of meso-structure and a new meso-contact constitutive model. The contact constitutive structure uses the same mathematical structure under different loading conditions to provide better simulation accuracy. (3) the code based on FISH language is written to simulate the loading condition of SCB test. The DEM virtual test method of asphalt mixture is formed by introducing the digital model of asphalt mixture mentioned above and the mesoscopic parameters calibrated by indoor test, and the reliability of virtual test method is verified. (4) with the help of the virtual test method developed above, Porosity is studied by changing porosity, pore size, pore distribution, aggregate orientation angle, aggregate flatness, aggregate content, aggregate distribution, etc. The influence of the meso-structure of asphalt mixture such as aggregate geometry and distribution on its fracture performance and crack initiation and development law. (5) taking contact force network as the research object, analyzing the structure characteristics of asphalt mixture aggregate, using orthogonal test method, The effects of different components on mortar properties are analyzed. Then the composition of asphalt mixture is optimized and verified by routine laboratory test.
【学位授予单位】：东南大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：U414

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