沥青混合料弯曲疲劳性能演化规律的宏细观试验表征  

Macro-and meso-scale experimental characterization of bending fatigue behavior evolution law for asphalt mixture

作　　者：冯卫东 菅永明 龚华勇 FENG Weidong;JIAN Yongming;GONG Huayong(Guizhou Ziwang Expressway Construction Co.,Ltd.,Guiyang 550800,China)

机构地区：[1]贵州紫望高速公路建设有限公司,贵州贵阳550800

出　　处：《铁道科学与工程学报》2022年第10期2984-2994,共11页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(51908558);贵州省交通运输厅科技项目(2019-122-006)。

摘　　要：沥青混合料疲劳寿命是表征沥青路面性能的重要指标。为了揭示沥青混合料在弯拉应力作用下的疲劳开裂演化规律,基于室内四点弯曲疲劳试验,考虑5种应变水平,研究沥青混合料劲度模量随疲劳寿命比的衰减规律。定量分析不同应变水平下劲度模量衰减的三阶段特征,即疲劳寿命比少于10%的劲度模量迅速衰减阶段、劲度模量呈现线性下降趋势阶段以及疲劳寿命比大于90%的快速下降阶段。基于室内四点弯曲试验,采用离散元技术建立沥青混合料三维小梁弯曲模型。同时开展间接拉伸与蠕变试验获取了离散元模型材料参数,并实现宏观材料参数与细观参数转换。通过离散元计算获得劲度模量和相位角的衰变曲线,与室内试验结果进行对比,验证了本文模型的正确性。通过分析沥青混合料弯曲疲劳过程中力链的发展表明,在疲劳寿命比达到0.7~0.8,集料和沥青砂浆之间的最大接触力超过该点的黏结力,力链发生断裂,造成裂缝贯通,使得沥青混合料发生断裂。通过分析沥青混合料裂隙碎片的生成和发育,结果表明在疲劳寿命比0~0.2之间,裂隙碎片只有少量生成,在疲劳寿命比0.2~0.8之间,裂隙碎片个数呈线性快速增加,随后裂隙碎片增加的速度逐渐降低,裂隙碎片逐渐贯通形成宏观断裂裂缝。研究结果为全面了解沥青混合料的疲劳破坏机理提供理论依据。The fatigue life of asphalt mixture is an important index to characterize the performance of asphalt pavement.In order to reveal the evolution law of fatigue cracking of asphalt mixture under flexural and tensile stress,the attenuation law of stiffness modulus of asphalt mixture with fatigue life ratio was studied based on four-point bending fatigue test in laboratory by considering five stain levels.The three-stage characteristics of stiffness modulus attenuation under different strain levels were quantitatively analyzed,which was classified as the rapid decrease when the fatigue life ratio was less than 10%,the stage of linearly deceasing stiffness modulus,and the fast decreasing stage when the fatigue life ratio was more than 90%,respectively.Furthermore,based on laboratory four-point bending fatigue test,a three-dimensional trabecular model of asphalt mixture was established by discrete element method.Meanwhile,the material parameters of discrete element model were obtained by indirect tensile and creep tests,and the conversion between macroscopic material parameters and microscopic parameters was conducted.Then,the degradation curve of stiffness modulus and phase angle were calculated and compared against the laboratory test results to verify the correctness of the proposed DEM model.Through analyzing the development of force chain in the process of bending fatigue of asphalt mixture,it was found that when the fatigue life ratio reaches 0.7~0.8,the maximum contact force between aggregate and asphalt mortar exceeds the adhesive force resulting in the connection of cracks,and the asphalt mixture breaks.Then,by analyzing the generation and development of fracture fragments in asphalt mixture,the results show that only a small amount of fracture fragments are generated when the fatigue life ratio is 0 to 0.2.When the fatigue life ratio is 0.2 to 0.8,the number of fracture fragments increases linearly and rapidly,and then the increasing rate of fracture fragments decreases gradually,and fracture fragments are gra

关 键 词：沥青混合料 四点弯曲疲劳试验 劲度模量 离散元法 疲劳开裂 

分 类 号：U41[交通运输工程—道路与铁道工程]