考虑荷载作用的沥青混合料冻融损伤特性研究

Research on freeze-thaw damage characteristics of asphalt mixture considering load action

针对寒区道路工程中的沥青路面冻融受荷损伤问题,借助细观损伤力学和宏观统计随机损伤模型,建立了冻融与荷载耦合作用下的沥青混合料损伤本构关系和损伤演化方程;探讨了冻融循环次数、应变和油石比影响下的沥青混合料冻融受荷损伤劣化机理。研究表明:冻融循环疲劳损伤累积和荷载作用于带有微缺陷粗集料界面附近产生的应力集中加剧了沥青混合料总损伤劣化程度。冻融循环20次之后,损伤度变化不大,基本趋于恒定;相同损伤程度时,应变值随冻融次数的增加而减小。油石比对总损伤影响显著,当油石比相对较小时,以冻融破坏为主;当油石比较大时,以受荷破损为主。研究成果可为寒区沥青路面抗冻设计、性能评价及养护维修时机选择提供参考。

In the light of the freeze-thaw and loading damage problem of asphalt pavement in cold areas,by means of meso-damage mechanics and macroscopic statistical stochastic damage model,the damage constitutive relation and damage evolution equation of asphalt mixture under coupling action of freeze-thaw and loading are established.The damage degradation mechanism of freeze-thaw and loading asphalt mixture under the influence of freeze-thaw cycles,strain and asphalt aggregate ratio are discussed.It is shown that the fatigue damage accumulation of freeze-thaw cycling and the stress concentration caused by loading,which acted on the coarse aggregate interface that carrying micro defects aggravated the total damage degradation of asphalt mixture.The damage degree does not changes greatly and tends to be constant gradually after 20 cycles,but the strain value decreases with an increasing of freeze-thaw cycles under the same damage degree.The asphalt aggregate ratio has a significant impact on total damage degree,it gives priority to freeze-thaw damage when asphalt aggregate ratio is relatively small,whereas the damage mainly caused by load when it is larger.The research results can provide a reference for asphalt pavement anti-freezing design,the performance evaluation and the selection of maintenance time in cold regions.