多因素耦合作用下沥青疲劳损伤—自愈—失效行为特征判别及统一模型

The damage-healing potential of asphalt binder is crucial for observing and understanding the fatigue lives discrepancy of asphalt paving materials respectively measured from laboratory fatigue testing and actual field pavement. The healing effect is still not covered into the current fatigue test protocols of asphalt binder and concrete, which restricts the accurate fatigue performance prediction of asphalt pavement structure and materials. In this proposed study, firstly the "viscoelastic recovery" and "damage-healing recovery", which simultaneous occurs during the healing rest period, are to be identified and distinguished based on the elastic-viscoelastic corresponding principle. Then the continuum damage mechanics will be employed to precisely characterize the "damage-healing" behavior. The damage state of asphalt binder will be divided based on the cohesive fatigue failure threshold and the healing behavior differences before and after fatigue failure occurrence will be compared and analyzed. Secondly, the rest time-damage state-temperature-aging superposition principle will be explored in the healing phase and attempted to apply for developing an unified healing mastercurve model of asphalt binder under coupling effects of multiple factors, based on which an efficient test procedure and data interpretation for representing the "critical healing index" of asphalt binder will be developed. Finally, integrating the developed healing functions into the current constitutive model of fatigue damage and failure behavior, the predictive approach for fatigue life of asphalt binder will be further refined. This proposed research will provide a fundamental understanding and an effective mean to predict the damage healing behavior of asphalt binder under the realistic condition of in-service field pavement, which also contributes to the fatigue durability design of asphalt paving materials.

沥青的损伤自愈潜力对认识和理解室内外沥青路面材料疲劳寿命的偏差尤为重要，目前室内沥青及沥青混凝土疲劳试验还未考虑自愈因素的影响，制约着沥青路面结构与材料疲劳性能的准确预测。本研究首先基于弹性-粘弹性对应准则对自愈间歇期内沥青“粘弹性恢复”和“损伤自愈”进行判断和识别，应用连续介质损伤力学手段建立沥青“损伤自愈”的精细表征方法，并以“内聚力疲劳失效”为临界条件对沥青损伤状态进行划分，分析和揭示疲劳失效发生前后沥青差异化自愈行为；然后尝试在自愈过程应用“间歇时间-损伤状态-温度-老化”等效原理，探索建立多因素耦合作用下沥青“自愈主曲线统一模型”以及快速有效测算沥青“关键自愈指数”的试验方法及指标计算方法；最后考虑自愈对沥青疲劳损伤及失效行为本构关系的影响，改进沥青疲劳寿命预估方法。本研究不仅为预测路面真实服役状态下沥青疲劳损伤自愈行为奠定理论基础，也为沥青路面材料抗疲劳耐久性设计做出贡献。

动态重复荷载作用下沥青疲劳损伤及自愈特性对于深入理解和掌握沥青路面全寿命周期抗疲劳服役性能演变至关重要。本项目即围绕沥青疲劳及自愈行为模型构建过程中的关键科学问题，首先在现有加速疲劳试验方法基础上，首次提出了快速测评沥青自愈性能的试验方法及“损伤自愈百分比”评价指标以精细化表征沥青在不同损伤状态和间歇期时长条件下的自愈性能；进而通过研究不同工况下的沥青差异化自愈行为特征，构建了基于“损伤-间歇等效原理”的沥青自愈主曲线理论与方法，统一了损伤状态和间歇期时长对沥青自愈行为的影响，并建立了以“自愈速率”为代表的沥青自愈特性评价指标体系；同时通过沥青微观化学特性和不同沥青种类、不同老化状态下的自愈行为验证，初步提出并验证了以“自愈速率”指标作为沥青“关键自愈指数”的科学有效性；最后，综合运用黏弹性力学和连续介质损伤力学全面构建了沥青疲劳损伤-自愈-失效行为特征判别方法，提出了综合考虑沥青线黏弹性、疲劳损伤演化、失效发生机理及自愈潜力的统一行为模型。本项目研究成果为今后深入理解和预测路面真实服役状态下的沥青自愈行为奠定理论基础，并为我国未来智能道路建设中的仿生自愈合沥青路面新技术提供理论支撑。