多频率重复荷载作用下布敦岩沥青混凝土宏细观开裂特性分析

Analysis of macro-fine cracking characteristics of Butun rock asphalt concrete under repetitive loading at multiple frequencies

针对布敦岩沥青混凝土路面在不同工况下的使用寿命问题,对多种路用环境及不同频率重复荷载作用下布敦岩沥青混凝土小梁试件进行三点弯曲重复加载试验,采用数字图像相关(digital image correlation,DIC)法分别对布敦岩沥青混凝土、基质沥青混凝土和SBS改性沥青混凝土在5种路用环境下的疲劳损伤进行分析。结果表明:在不同路用环境和多频率的作用下,疲劳寿命排序为SBS改性沥青混凝土>布敦岩沥青混凝土>基质沥青混凝土;布敦岩的掺加对沥青混凝土疲劳性能起到了提升作用,但对车速变化的敏感程度较强;布敦岩沥青能有效提升沥青混凝土的抗疲劳开裂性能;同种材料在相同重复荷载作用次数时的损伤程度随着加载频率的增加而减小;布敦岩的掺加可以提高混合料的抗损伤能力,延缓沥青混凝土出现加速开裂的时间点;布敦岩沥青混凝土宏观裂纹出现的时间点为重复荷载次数占比为70%时。研究成果有利于工程提前制定相应的防治措施。

To address the problem related to the service life of Butun rock asphalt concrete pavement under different operating conditions,the fatigue damages of Butun rock asphalt concrete,matrix asphalt concrete,and SBS modified asphalt concrete were analyzed under five types of road environments and different frequencies of repetitive loads by three-point bending repetitive loading tests of Butun rock asphalt concrete beam specimens combined with digital image correlation(DIC)technique.The fatigue damage of Butun rock asphalt concrete,matrix asphalt concrete and SBS modified asphalt concrete in five road environments were analyzed by DIC technique.The results show that the fatigue life under different road environments and multi-frequency is in the order of SBSmodified asphalt concrete>Butun rock asphalt concrete>base asphalt concrete.The fatigue performance of asphalt concrete is improved by the addition of Butun rock,but the sensitivity to the change of vehicle speed is strong.The fatigue cracking resistance of asphalt concrete is enhanced by the addition of Butun rock.The degree of damage same material under the same number of repetitive loading action decreases with the increase in loading frequency.Butun rock admixture can improve the mixture’s resistance to damage and delay the asphalt concrete appeared accelerated cracking time point.Macroscopic cracks appeares when the repetitive loads accounted for 70%of the role of the number of times for Butun rock asphalt concrete.The findings herein can be conducive to the developments of appropriate prevention and control measures in advance in practical projects.