基于离散元方法的沥青混合料矢量场细观分析

Mesoscopic analysis on vector field of asphalt mixture using discrete element method

为了从细观角度描述沥青混合料中集料和砂浆的矢量场随加载时间的变化,以简单性能试验(SPT)测定沥青混合料的动态模量和相位角,采用数字图像处理和Matlab提取沥青混合料截面图像的像素坐标,利用离散元方法重构沥青混合料数字试件,在验证数字试件合理性的基础上,通过追踪集料和砂浆的位移场和速度场,分析了不同加载时间集料和砂浆矢量场的差异。研究结果表明:沥青混合料动态模量的预测值与实测值仅相差4.76%,相位角的预测值与实测值的差异为8.57%;集料和砂浆的位移场方向主要沿竖向向下,由上至下位移减小,整体集料与典型集料、整体砂浆与典型砂浆的最大位移相差较小,最大差异分别为5.20%和2.45%,砂浆的位移稍大于集料;随着加载时间的增大,整体集料和砂浆、典型集料和砂浆的最大速度均逐渐增大,砂浆的速度基本大于集料。

In order to describe the vector field changes of aggregate and sand mastic in asphalt mixture with the loading time from the microscopic viewpoint, the dynamie modulus and phase angle of as- phalt mixture were measured by simple performance test （SPT）. Then the digital image processing and Matlab were employed to extract the pixel coordinates of asphalt mixture section image, and the digital specimen of asphalt mixture was reconstructed by the discrete element method. The vector field changes of aggregate and sand mastie were analyzed at different loading time by tracking their displacement and velocity field based on verifying the rationality of digital specimen. The results show that the predicted and measured values of dynamic modulus differ only by 4. 76% , and the difference between the predicted and measured values of phase angle is 8. 57 %. The displacementfield directions of aggregates and sand mastic are mainly along the vertical and downward direc- tion, and the displacement decreases from top to bottom. The maximum displacement difference between the overall aggregates and typical aggregate, and the overall sand mastic and typical sand mastic are smaller, and the largest difference is 5.20% and 2.45% respectively. In addition, the maximum displacement of sand mastic is slightly larger than aggregates. The maximum velocities of the overall aggregates and sand mastic and the typical aggregate and sand mastic increase with the increase of loading time, and the velocity of sand mastic is greater than that of aggregate basi cally. 4 tabs, 8 figs, 15 refs.