骨料形状对沥青混合料性能影响的离散元研究

发布时间：2018-03-11 14:30

本文选题：沥青混合料　切入点：离散单元法　出处：《大连理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：沥青混合料(HMA)是一种由沥青粘结料、骨料颗粒以及填料等组成的多相复合材料,其中粗骨料的质量和体积约占总量的90%,沥青混合料的性能很大程度上取决于粗骨料的性质。研究表明,在所有影响混合料性能的因素中,形状特征被认为是仅次于骨料级配的第二大影响因素。目前,关于骨料形状对沥青混合料性能影响的研究大都是通过室内试验完成的,得到的结果稳定性和再现性较差,造成了一定的人力物力浪费。近年来,离散单元法在沥青路面研究中应用广泛。这种方法不但可以模拟骨料级配,还能够研究骨料形状特征对HMA性能的影响。本文首先研究了采用球形颗粒粘结成块来构建任意形状粗骨料颗粒的方法。与以往研究不同的是,这里先随机生成多面体壳,而后应用非线性约束优化的理论,将用于填充多面体壳的球形颗粒数目降到最少,从而得到多面体颗粒。文中给出了相应的算法,并计算得到了多面体颗粒的相关形状参数。为了研究颗粒形状参数与HMA宏观力学性能之间的关系,文中基于离散单元法建立了HMA圆柱形模型,在PFC3D软件环境下进行三轴试验模拟,建立了沥青混合料抗剪强度随粗骨料颗粒的长细比和扁平比的分布云图,并给出了它们之间的函数表达式。根据计算结果,提出了一个新的针片状认定指标Q,同时也分析了级配设计时粗骨料颗粒形状控制的基本原则。数值计算结果与实验结果的对比证明了结果的合理性。
[Abstract]:Asphalt mixture (HMA) is a kind of multiphase composite composed of bituminous binder, aggregate particle and filler. The quality and volume of coarse aggregate account for about 90% of the total amount, and the performance of asphalt mixture depends largely on the properties of coarse aggregate. Shape characteristics are considered to be the second most important influencing factor after aggregate gradation. At present, most of the researches on the effect of aggregate shape on asphalt mixture performance are completed through laboratory tests, and the results obtained are less stable and reproducible. In recent years, discrete element method has been widely used in asphalt pavement research. This method can not only simulate aggregate gradation, It is also possible to study the effect of shape characteristics of aggregate on the properties of HMA. In this paper, we first study the method of forming arbitrary coarse aggregate particles by bonding spherical particles into blocks. Different from previous studies, polyhedron shells are generated at random here. Then, by using the theory of nonlinear constrained optimization, the number of spherical particles filled with polyhedron shell is reduced to the minimum, and the polyhedron particles are obtained. In order to study the relationship between the shape parameters of polyhedron particles and the macroscopic mechanical properties of HMA, the HMA cylindrical model is established based on the discrete element method. The distribution of shear strength of asphalt mixture with the slenderness ratio and flat ratio of coarse aggregate particles was established by triaxial test simulation under the PFC3D software environment, and the functional expressions between them were given. In this paper, a new needle shape determination index Q is proposed, and the basic principle of coarse aggregate shape control in gradation design is also analyzed. The comparison of numerical results with experimental results proves the rationality of the results.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U414

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