基于耗散能原理的沥青混合料永久变形硬化-损伤模型

Permanent deformation of asphalt mixture is the coupling result of strain hardening and damage softening. The influence of damage is often ignored in the study of asphalt permanent deformation, resulting in the failure in the description of the three-phase permanent deformation characteristics of the asphalt mixture. Therefore, it affects the evaluation accuracy of the permanent deformation resistance. Aiming to solve this problem, this research will propose a method to separate the viscoelastic dissipated energy and plastic dissipated energy based on the obtained data from repeated loading test with rest duration, combining viscoelasto-plastic theory and dissipation energy principle. On this basis, the change of viscoelastic dissipated energy and the evolution of plastic dissipated energy under different temperatures and different stress levels will be studied and the strain hardening and damage softening variables considering the effects of temperature and stress level will be introduced as well. From the perspective of dissipated energy, the coupling mechanism of strain hardening and damage softening of asphalt permanent deformation will be studied and thus the hardening-damage model of asphalt permanent deformation will be established based on the dissipated energy principle. Expected research results can precisely describe the three-phase permanent deformation characteristics of the asphalt mixture and provide theoretical guidance and technical support for further accurate evaluation of the permanent deformation resistance of the asphalt mixture.

沥青混合料永久变形是应变硬化和损伤软化耦合作用的结果。目前对沥青混合料永久变形的研究忽略了损伤的因素，未能全面准确地描述沥青混合料三阶段永久变形特征，从而影响了沥青混合料抗永久变形能力评价的准确性。针对此问题，本项目将基于间歇重复加载试验数据，结合粘弹塑性理论和耗散能原理，提出分离粘弹性耗散能和塑性耗散能的方法。在此基础上，研究不同温度、不同应力水平下的沥青混合料粘弹性耗散能变化量及塑性耗散能的演化规律，引入考虑温度和应力影响的应变硬化变量和损伤软化变量，从耗散能角度揭示沥青混合料永久变形的应变硬化和损伤软化的耦合机制，由此建立基于耗散能原理的沥青混合料永久变形硬化-损伤模型。预期研究成果可以全面准确地描述沥青混合料三阶段永久变形特征，为准确评价沥青混合料的抗永久变形能力提供理论依据和技术支撑。

本项目从宏观层面上发现了沥青混合料永久变形三阶段模型和沥青混合料的应变硬化和损伤软化密切相关性，并提出分别对应于沥青材料的塑性耗散能和粘弹性耗散能，基于此提出了塑性耗散能和粘弹耗散能的分离方法，与此同时，提出了应变硬化和损伤软化的耦合机理；根据累积塑性耗散能和累积粘弹耗散能与加载次数的对应关系，结合永久变形一般模型，建立了考虑损伤的沥青混合料永久变形模型，通过与实际测试数据进行拟合，从侧面验证了塑性耗散能转化为塑性功，引起材料的应变硬化，粘弹耗散能主要转化为沥青材料内部损伤所需要的能量。本项目研究成果对正确认识沥青混合料的力学行为以及内在机理开拓了新的研究思路。