自然落料状态下路面混合料离析研究

发布时间：2018-03-07 21:51

本文选题：路面混合料　切入点：离析　出处：《长安大学》2014年硕士论文　论文类型：学位论文

【摘要】：路面混合料的均匀性严重影响路面的路用性能。有效、定量地评价路面混合料均匀性一直是道路工程界的关键问题之一。本文基于图像处理技术对路面混合料截面图像进行处理和计算，研究混合料中各档粒径颗粒的分布状态。提出采用混合均匀度作为离析程度的评价指标，，计算每一档粒径的混合均匀度，将各档集料均匀度加权平均后得到整个截面的混合均匀度。将多个截面的均匀度加权平均可得到整个试件的均匀度。混合料在自然下落堆积状态下极易发生离析现象，采用自制的漏斗试验装置和不同形状的颗粒进行室内模拟试验，研究堆积角对离析的影响。通过自制的层状圆环试验装置和经过染色处理的级配集料进行下落堆积试验，研究混合料级配对离析的影响。由于在实际室内试验时，改变材料性质和级配等需要进行大量的试验，本文通过离散元PFC2D软件建立模型模拟不同摩擦系数和多种级配集料，将离散元应用于路面混合料均匀性评价中。研究结果表明：越不规则的颗粒堆积形成的堆积角越大，颗粒越接近于球形堆积形成的堆积角就越小；在最大堆积角范围内，堆积角越大，混合均匀度越大，离析程度越小，建立了堆积角和离析程度预估模型。根据级配分形理论和图像计算可知，密级配、半开级配、开级配和间断级配四种级配相比，Hs (AM16)＞Hs (OGFC16)＞Hs (AC16)＞Hs (SMA16)，建立了不同级配分形维数与离析程度之间的关系式。室内模拟试验为离散元模型中各参数的设置提供了依据，模拟试验计算结果和室内试验结果相一致，验证了离散元模型的可行性和正确性。
[Abstract]:The uniformity of pavement mixture seriously affects the pavement performance. Quantitative evaluation of pavement mixture uniformity has been one of the key problems in road engineering. The distribution state of particle size in each stage of mixture is studied. The mixing uniformity degree is used as the evaluation index of segregation degree, and the mixing uniformity degree of each grade particle size is calculated. The mixing uniformity of the whole section can be obtained by weighting the evenness of each grade aggregate, and the uniformity of the whole specimen can be obtained by the weighted average of the evenness of several sections. The mixture is prone to segregation under the condition of natural falling and stacking. The self-made funnel test device and the different shapes of particles are used to carry out the indoor simulation test. The effect of stacking angle on segregation is studied. The effect of mixture gradation on segregation is studied by means of self-made layer ring test device and dyeing gradation aggregate. A lot of experiments are needed to change the properties and gradation of materials. In this paper, the discrete element (PFC2D) software is used to establish a model to simulate different friction coefficients and various gradation aggregates, and the discrete element is applied to the evaluation of pavement mixture uniformity. The results show that the larger the stacking angle is, the smaller the accumulation angle is, and the larger the accumulation angle is, the greater the mixing uniformity is and the smaller the segregation degree is. According to the fractal theory of gradation and image calculation, it is known that dense gradation, semi-open gradation, The relationship between the fractal dimension of different gradation and the degree of segregation is established. The laboratory simulation test provides the basis for setting up the parameters in the discrete element model, and the relationship between the fractal dimension of different gradation and the degree of segregation is established by comparing the four grades of open gradation and discontinuous gradation: Hs / AM16 > HS / OGFC16) > HS / AC16) > HS / SMA _ (16) > H _ s / C _ (16) > HS / SMA _ (16). The simulation results are consistent with the results of laboratory tests, and the feasibility and correctness of the discrete element model are verified.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U414

【参考文献】