沥青混合料集料颗粒行为及区域划分研究

发布时间：2018-05-17 00:36

本文选题：沥青混合料 + 数字图像处理　；参考：《长安大学》2014年硕士论文

【摘要】：沥青混合料是由集料、空隙和沥青胶浆组成的三相复合材料，是一种典型的非均质、不连续的颗粒性质的材料。但是，现行弹性层状体系理论假设沥青混合料为各向同性的均质材料，，与实际情况明显不符。本文首先成型连续级配和间断级配沥青混合料车辙试件，经切割、组装后再开展不同温度和荷载条件下的车辙试验，定性分析了基于位移等值线的试件内部颗粒运动规律；结合数字图像处理技术、统计方法，定量分析了试件内部颗粒的运动规律，据此对车辙试验板的均质区、非均质区进行了划分；最后，采用PFC离散元程序，模拟分析了两种不同级配沥青混合料的车辙试验，进一步验证了均质区和非均质区划分方法。研究主要结论如下：（1）、在相同外界条件及荷载作用下，间断级配混合料相比于密级配混合料发生不规则颗粒运动的区域略大。且温度的升高或作用荷载的增大都会引起混合料内部非均质区范围增加。（2）、本文中所研究的几种混合料经压实后，内部颗粒主轴角度主要集中在80-100°范围内；加载位置下方颗粒Y方向位移（竖向）基本朝下，该区域内位移方向角分布比较均匀；而加载位置两侧范围内，颗粒竖向位移存在着一定负向位移（朝上运动），且位移角度主要集中在0-50°之内，即加载位置两侧颗粒位移主要向两侧扩散，并有部分颗粒被朝向挤压。（3）、采用采用灰色关联分析方法，对温度和荷载两因素与不同类型混合料内部非均质区范围的关联程度进行分析可知，密级配混合料对温度的敏感性与荷载的敏感性差别相对较小，而间断级配混合料受荷载的影响明显强于温度对其的影响。（4）、离散元模拟结果表明，沥青混合料中力链的传递以及颗粒位移矢量规律与真实试验结果较为吻合，离散元在一定程度上能够模拟真实加载过程中材料内部颗粒运动的规律。
[Abstract]:Asphalt mixture is a three-phase composite composed of aggregate, void and asphalt paste. It is a typical heterogeneous and discontinuous material with particle properties. However, the present theory of elastic layered system assumes that the asphalt mixture is isotropic homogeneous material, which is obviously inconsistent with the actual situation. In this paper, the continuous gradation and discontinuous gradation of asphalt mixture rutting specimens are first formed. After cutting and assembling, the rutting tests under different temperature and load conditions are carried out, and the internal particle motion law of the specimens based on displacement isoline is analyzed qualitatively. Combined with digital image processing technology and statistical method, the motion law of particles inside the specimen is quantitatively analyzed, according to which the homogeneous and heterogeneous areas of rutting test plate are divided. Finally, PFC discrete element program is used. The rutting tests of two kinds of asphalt mixtures with different gradation are simulated and analyzed, and the method of dividing homogeneous and heterogeneous areas is further verified. The main findings of the study are as follows: Under the same external conditions and loads, the area of irregular particle movement of discontinuous gradation mixture is slightly larger than that of dense gradation mixture. And the increase of temperature or the increase of the action load will cause the increase of the range of the heterogeneous zone inside the mixture. After compaction of several kinds of mixtures studied in this paper, the angle of main axis of internal particles is mainly concentrated in the range of 80-100 掳, the displacement of Y direction (vertical) is basically downward under the loading position, and the angular distribution of displacement direction in this area is relatively uniform. However, in the range of both sides of loading position, the vertical displacement of particles has certain negative displacement (moving upward, and the displacement angle is mainly within 0-50 掳), that is, the displacement of both sides of the loading position mainly diffuses to both sides, and some particles are extruded towards the two sides. In this paper, the grey correlation analysis method is used to analyze the correlation degree between temperature and load and the range of internal heterogeneity of different kinds of mixtures. The sensitivity of dense gradation mixture to temperature and load is relatively small, while the influence of discontinuous gradation mixture is stronger than that of temperature. The simulation results of discrete element show that the law of force chain transfer and particle displacement vector in asphalt mixture is in good agreement with the real test results, and the discrete element can simulate the law of particle movement in the course of real loading to some extent.
【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

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