基于分形维数的密级配沥青混凝土设计指标预估  

Prediction of Dense Graded Asphalt Concrete Design Index Based on Fractal Dimension

作　　者：柴智[1] Chai Zhi(China Academy of Transportation Sciences,Beijing 100029,China)

机构地区：[1]交通运输部科学研究院,北京100029

出　　处：《交通运输研究》2020年第5期28-37,共10页Transport Research

摘　　要：通过研究沥青混凝土原材料参数与其设计指标之间的相关关系,以简化沥青混凝土配合比设计过程。通过系统调研多条高速公路密级配沥青混凝土的应用情况,采用分形理论表征矿料级配特性,明确现有工程常用密级配沥青混凝土矿料分形维数及油石比分布情况,并基于AC-13型及AC-20型沥青混凝土构建沥青混凝土设计指标预估方程。结果表明,不同密级配沥青混凝土均可采用唯一分形维数对其级配特性进行表征,工程采用的密级配沥青混凝土的矿料分形维数基本在2.44~2.54之间;随着油石比的增大,标准条件下成型的密级配沥青混凝土的空隙率及饱和度逐渐下降,可基于空隙率及饱和度预估方程反推最佳油石比;矿料分形维数对沥青混凝土的稳定度影响较大,随着矿料分形维数的增大,其稳定度呈增长趋势;在生产配合比验证阶段,可基于稳定度试验反推混凝土分形维数并对比生产配合比与设计配合比的差异性,以优化现阶段配合比验证工序。In order to simplify the design process of asphalt concrete mix proportion,the correlation between raw material parameters and design indexes of asphalt concrete were studied.The application of dense graded asphalt concrete in several expressways was systematically investigated.Fractal theory was used to characterize the mineral aggregate gradation.The fractal dimension and asphalt aggregate ratio distribution of dense graded asphalt concrete commonly used in existing projects were clarified.Based on AC-13 and AC-20 asphalt concrete,the design index prediction equation of asphalt concrete was constructed.The results show that:the unique fractal dimension can be used to characterize the gradation of different dense graded asphalt concrete,the fractal dimension of mineral aggregate of dense graded asphalt concrete used in engineering is basically between 2.44 and 2.54;with the increase of asphalt aggregate ratio,the void ratio and saturation of dense graded asphalt concrete formed under standard conditions gradually decrease,thus the optimum asphalt-aggregate ratio can be predicted based on void ratio and saturation equation;the fractal dimension of mineral aggregate has a significant impact on the stability of asphalt concrete,which grows with the increase of the fractal dimension of mineral aggregate;in the production mix proportion verification stage,the concrete fractal dimension can be reversely deduced based on the stability test,and the difference between the production mix proportion and the design mix ratio can be compared to optimize the mix proportion verification process at the present stage.

关 键 词：沥青混凝土 密级配 矿料级配 分形 分形维数 路用性能 

分 类 号：U416.217[交通运输工程—道路与铁道工程]