基于离散元的沥青混合料高温性能研究

发布时间：2018-04-03 08:35

本文选题：沥青混合料　切入点：高温性能　出处：《东南大学》2015年硕士论文

【摘要】：沥青混合料高温性能不足会导致沥青路面在行车荷载的作用下出现车辙,起皱,推移,拥包等病害,其中车辙会影响路面的平整度,降低路面的抗滑能力,甚至影响行车的舒适和安全。传统的室内试验方法不仅需要消耗大量时间和成本,而且鉴于沥青混合料材料的不均匀性和复杂性,室内研究方法的重复性和再现性较差。离散元方法可为沥青混合料的性能分析提供辅助手段,对提高沥青路面的使用性能具有重要意义。论文利用离散元方法对沥青混合料的高温性能进行了分析：首先,基于沥青混合料三相组成的结构特征,构建代表不同组分的模型,最终得到了具有级配特征以及粗集料表征能力的沥青混合料离散元颗粒模型。其次,通过完成室内试验,通过宏观参数与微观参数的转化关系,得到沥青混合料虚拟试件各组分间的微观接触参数,将室内试验与虚拟试验结果进行对比。再次,通过变化不同的级配及混合料的油石比,进行相应数字试件的虚拟单轴蠕变试验,分析各档集料和沥青用量对混合料高温性能影响的主次关系。其中,沥青用量对高温性能影响最大,其次是4.75-9.5mm集料,再次为9.5-13.2mm集料。最后,保证沥青砂浆的微观接触参数不变,变化沥青混合料2.36mm以上粗集料的含量,分析虚拟试验的结果,并对不同级配沥青混合料的接触力,速率,位移参数进行微观分析。研究发现：接触力,速率,位移都可以预测沥青混合料的高温性能。若砂浆内部、砂浆与集料之间的受力越均匀,或者粗集料之间的接触力均值越小,沥青混合料的高温性能越好；若粗集料的竖向位移和移动角越小,沥青混合料的高温性能越好；若试件的宏观应变速率或集料平动、转动速率越小,且集料在受荷载方向平动达到第一个速率峰值时昕对应的时步数更小,沥青混合料的高温性能越好。另外,对高温荷载下不同粒径粗集料的相应进行分析,可以发现：粗集料的粒径越小,发生大范围竖向位移的概率越小：较细粒径的粗集料更易发生横向移动,其转动角更大。在进行中面层AC-20沥青混合料的级配设计时,论文建议4.75-9.5mm,9.5-13.2mmm集料质量分数不低于集料总质量的20%和15%。在控制集料4.75mm筛孔通过率低于45%的同时,建议2.36-4.75nm集料的质量分数不低于总质量的15%。
[Abstract]:The lack of high temperature performance of asphalt mixture will lead to rutting, wrinkling, moving, packing and other diseases of asphalt pavement under the action of driving load, among which rutting will affect the smoothness of road surface and reduce the ability of road surface to resist sliding.Even affect the comfort and safety of driving.The traditional indoor test method not only consumes a lot of time and cost, but also has poor repeatability and reproducibility due to the heterogeneity and complexity of asphalt mixture materials.Discrete element method can provide auxiliary means for performance analysis of asphalt mixture, and it is of great significance to improve the performance of asphalt pavement.In this paper, the high temperature performance of asphalt mixture is analyzed by discrete element method. Firstly, based on the structural characteristics of the three-phase composition of asphalt mixture, a model representing different components is constructed.Finally, the discrete element particle model of asphalt mixture with gradation and coarse aggregate characterization is obtained.Secondly, the microscopic contact parameters of each component of virtual asphalt mixture are obtained by completing the indoor test and transforming the macro and micro parameters, and the results of indoor test and virtual test are compared.Thirdly, the virtual uniaxial creep tests of the corresponding digital specimens are carried out by changing the gradation and the asphalt ratio of the mixture, and the primary and secondary relationship of the influence of the aggregate and asphalt content on the high temperature performance of the mixture is analyzed.Among them, asphalt content has the greatest influence on high temperature performance, followed by 4.75-9.5mm aggregate and 9.5-13.2mm aggregate.Finally, the microcosmic contact parameters of asphalt mortar are kept constant, the content of coarse aggregate above 2.36mm is changed, the results of virtual test are analyzed, and the contact force, velocity and displacement parameters of asphalt mixture with different gradation are analyzed microscopically.It is found that contact force, rate and displacement can predict the high temperature performance of asphalt mixture.If the internal force between mortar and aggregate is uniform, or the average contact force between coarse aggregate is smaller, the high temperature performance of asphalt mixture is better, if the vertical displacement and moving angle of coarse aggregate are smaller,The better the high temperature performance of asphalt mixture is, the smaller the rotation rate is if the macroscopic strain rate of the specimen or the translational movement of the aggregate, and the smaller the number of time steps corresponding to the first peak rate of the aggregate in the direction of load.The better the high temperature performance of asphalt mixture.In addition, the corresponding analysis of coarse aggregate with different particle size under high temperature load shows that the smaller the size of coarse aggregate is, the smaller the probability of occurrence of large vertical displacement is, and the more easily the coarse aggregate with smaller particle size moves laterally and its rotation angle is larger.When the gradation design of AC-20 asphalt mixture is carried out, it is suggested that the aggregate mass fraction of 4.75-9.5 mm and 9.5-13.2 mm should not be lower than 20% and 15% of the aggregate total mass.While controlling the pass rate of 4.75mm sieve hole less than 45%, it is suggested that the mass fraction of 2.36-4.75nm aggregate should not be lower than 15% of the total mass.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U414

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