水-力-热耦合作用下沥青混凝土细观损伤机理研究

Vehicles, water and temperature are the main factors which affect the properties of asphalt pavement. The coupling actions of them will result the coupling damage and destroy of asphalt pavement. Though the effect of single factor can be evaluated by the experimental method, the coupling damage mechanism of asphalt concrete is unclear. Therefore, the actual service state and characteristics of asphalt concrete are considered in this project. The effects of dynamic hydraulic pressure and temperature on the diffusion properties of moisture will be investigated with experiments. The effects of moisture on the bond strength of aggregate-binder system and the viscoelastic properties of mortar will also be determined using test method. In further, the moisture-mechanical damage constitutive relationship will be established. The damage model will be developed and validated using the second developed method. Finally, the model of asphalt concrete will be developed using the techniques of digital image processing. The coupling micromechanical damage mechanism will be investigated. Relationship between the micromechanical damage and macro indicators will be determined. This project will obtain the damage mechanism of asphalt concrete under the actions of dynamic hydraulic pressure and temperature directly. And the damaged of various factors will be decoupled. It is helpful for the improvement of evaluating method for anti-moisture damage performance. So, this project has the significant theoretical and practical value.

车辆荷载、降水和温度是影响沥青路面使用性能的主要因素，他们的共同作用将导致沥青路面的耦合损伤和破坏。试验分析虽能单独评价各因素影响，却无法明确各因素耦合作用导致的沥青混凝土内部损伤规律。因此，本研究从沥青混凝土实际使用状态和材料特点入手，采用试验方法探讨动水压力和温度对水扩散性能的影响，并分析水对集料-胶浆粘结强度和胶砂粘弹性能的影响规律，进而建立胶砂的水-力耦合损伤本构关系，对损伤本构关系进行二次开发与验证。最后，基于数字图像技术建立沥青混凝土细观模型，对水-力-热耦合作用下沥青混凝土的细观损伤机理进行演化分析，并确定细观损伤与宏观指标衰变之间的关系。本项目研究不仅可以明确动水压力和温度作用下的细观损伤机理，而且还能对不同因素进行解耦分析，有助于改进沥青混凝土的抗水损评价方法，具有重要的理论意义和工程应用价值。

暴露在自然环境中的沥青路面除了承受车辆荷载作用外，还承受外界环境因素如降雨及温度的影响，现有评价方法虽能单独评价各因素影响，却无法明确各因素耦合作用导致的沥青混凝土内部损伤规律。因此，探究沥青混凝土在水-力-热耦合作用下的损伤机理具有重要的现实意义。本项目通过研发压力渗透扩散测试装置，开展了水在沥青胶砂、混合料及集料内部的扩散规律研究，确定了温度及压力对水扩散系数的影响程度及规律。自行设计了温湿度环境控制箱，测定了绝对湿度条件下水汽在沥青胶砂、混合料及胶浆内部的扩散规律。探讨了集料-胶浆粘结强度随温度及水处理时间的变化规律，确定了油石界面粘结强度随浸水时长、冻融次数及盐溶液浓度的损伤规律。分析了干湿循环对沥青胶砂及混合料高温变形特征的影响规律。基于试验测试结果，开发了适用于沥青混合料的非线性粘弹性材料模型。对沥青混凝土在水-力-热耦合作用下的损伤机理进行了试验分析，利用CEL流-固耦合分析技术分析了沥青路面动水压力变化规律，基于高温蠕变试验、动态间接拉伸劲度模量试验、低温劈裂试验确定了干湿循环对沥青混合料高低温性能的损伤规律，为服役状态下沥青路面路用性能长期损伤状态评价提供了有效的参考依据。