粗集料形态特征及含量对沥青混合料压密行为的影响

Influence of Coarse Aggregate Morphological Characteristics and Content on the Compaction Behavior of Asphalt Mixtures

为探究粗集料形态特征及颗粒含量对沥青混合料压密行为的影响规律,利用智能颗粒对车辙试验进行测试,获取颗粒力学和运动响应数据,通过三维激光扫描设备及图像处理技术构建了不同形态特征的粗集料轮廓,利用离散元方法建立沥青混合料的车辙数字试件。对数字试件开展虚拟车辙试验,借助智能颗粒测试结果对模型预测精度进行校验,利用高精度模型研究粗集料形状及含量对混合料压密行为的影响规律,以数字试件内部应力与颗粒位移来评价混合料的抗变形性能,以单一集料平均接触点数量与力链大小为量化指标进行骨架接触特性分析。结果表明:智能颗粒测试结果能够有效验证预测模型的精度,加速度幅值实测与预测最大差异为0.0215 g;在车辙虚拟试验中,由立方体状集料成型的试件,其内部应力高于含其他形状集料的混合料,且具有较小的迁移自由度,在集料含量为40%时颗粒竖向及水平位移仅为3.65 mm、1.89 mm;集料含量会影响沥青混合料压密行为,沥青混合料抗车辙变形性能及骨架接触特性随立方体状集料含量的增加而提高,而当针状、片状或针片状集料颗粒含量大于20%时,性能出现明显衰变。

To investigate the influence of coarse aggregate morphological characteristics and particle content on the compacting behavior of asphalt mixture,smart rock was used to test the rutting test,obtain the particle mechanics and motion response data,construct coarse aggregate profiles with different morphological characteristics by 3D laser scanning equipment and image processing technology,and build digital specimens of asphalt mixture rutting by using discrete element method.Virtual rutting tests were carried out on the digital specimens,and the model prediction accuracy was verified with the help of smart particle test results.The high-precision model was used to study the influence of coarse aggregate shape and content on the compacting behavior of the mixture,and the internal stress and particle displacement of the digital specimens were used to evaluate the deformation resistance of the mixture,and the skeleton contact characteristics were analyzed with the average number of contact points of a single aggregate and the force chain size as quantitative indicators.The results show these as follows.Smart particle test results can effectively verify the accuracy of the prediction model,and the maximum difference between the measured and predicted acceleration amplitude is 0.0215 g.In the virtual test of rutting,the internal stresses of the specimens formed by cubic-shaped aggregates are higher than those of the mixes containing other shapes of aggregates,and they have smaller migration degrees of freedom,and the vertical and horizontal displacements of the particles are only 3.65 mm and 1.89 mm at 40%of the aggregates.The aggregate content affects the compacting behavior of asphalt mixes,and the rutting resistance and skeleton contact characteristics of asphalt mixes increase with the increase of cubic aggregate content,while the performance decays significantly when the content of needle-shaped,flaky or pin-like aggregate particles is greater than 20%.