“动载-环境”耦合下板式轨道充填层自密实混凝土性能演变与机制

Self-compacting concrete (SCC) filling layer is one of the most important structural parts in CRTS Ⅲ slab track. The properties evolution of SCC used in filling layers has great influence on stability of slab track structure. However, SCC used in filling layer need to be studied further when it is exposed to train dynamic load, water and temperature simultaneously.. In order to finish this project, related theories such as material science, physics chemistry and damage mechanics, and analysis methods such as simulation test, theoretical analysis and numerical calculation will be taken into account. The evolution of microstructure and macro mechanical properties of SCC coupling to train dynamic load, water and temperature is studied experimentally. The process of microstructure damage and mechanics is analyzed under the effect of train dynamic load, water and temperature. The relationship between microstructure damage and mechanics parameters evolution is also discussed intensively. Effect mechanism of water and temperature on deterioration of SCC is ascertained. Mechanism of microstructure damage and mechanics parameters evolution coupling to train dynamic load, water and temperature is revealed. Finally, improvement technical measures of SCC used in filling layer are put forward. . Results of this project would provide progressive technical supports for maintenance of CRTSⅢ slab track in operation and theoretical foundation for materials development used in slab track.

自密实混凝土充填层是CRTSⅢ型板式轨道的重要结构部件，其性能变化对轨道结构的稳定性有重要影响。目前人们对列车动载、水和温度耦合作用下充填层自密实混凝土性能的演变还需深入研究。. 本项目拟运用材料科学、物理化学以及损伤力学等理论，采用试验测试、理论分析和数值计算相结合的方法，对动荷载、水和温度耦合作用下充填层自密实混凝土微结构和力学性能的变化展开研究，分析动荷载、水和温度等因素作用下充填层自密实混凝土微结构损伤和宏观力学性能演变的过程，深入剖析两者之间的相互关系和影响，探明在水和温度作用下充填层自密实混凝土性能加速劣化的机理，揭示“动载-水-温度”耦合下充填层自密实混凝土微结构损伤与力学性能演变的机制，提出改善充填层自密实混凝土服役性能的技术措施。. 本项目的开展将为CRTSⅢ板式轨道运营期间的养护维修提供相应技术支撑并为板式轨道充填层材料的发展提供理论依据。

充填层是CRTSIII型板式轨道结构的核心部件，其中自密实混凝土是充填层的关键材料。随着CRTSIII型板式轨道结构在设计时速300km及以上高速铁路中获得广泛应用，环境与动荷载共同作用下充填层自密实混凝土性能演变及其稳定性越来越受到关注。本项目通过现场调研，结合试验系统研究了环境+动荷载（动荷载、水+动荷载、水/酸+动荷载、冻融、轴压荷载+冻融、冰冻+动荷载）等条件下，充填层自密实混凝土各项性能的变化，并基于等效应力和能量法等原理，建立了与试验结果拟合度较高自密实混凝土损伤本构模型。取得如下研究成果：①深入调研了昌赣客专和京沈客专CRTSIII型板式轨道充填层自密实混凝土的服役现状，得到了我国高铁基础结构在服役中面临的 “南湿”，“北冻”与列车动荷载耦合的典型服役特征。②测试了水/酸-动荷载共同作用下充填层自密实混凝土性能的变化，揭示了在水/酸-动荷载耦合下自密实混凝土性能变化的特征，探明了水和酸雨对充填层劣化的加速机制，提出了充填层自密实混凝土在水/酸-动荷载耦合的损伤本构模型。③测试了冻融、荷载+冻融，冰冻+动荷载共同作用下充填层自密实混凝土性能的变化，揭示了在荷载-冻融以及冰冻-动荷载共同作用下自密实混凝土性能的变化特征，探明了低温冻融对充填层劣化的加速机制，提出了充填层自密实混凝土在荷载-冻融耦合的下损伤本构模型。④建立了CRTS III型板式轨道有限元三维分析模型，通过带入试验测试数据，计算得到了CRTS III型板式轨道结构充填层自密实混凝土在环境-动荷载共同作用下力学性能的长期演变过程。. 项目的研究成果将进一步为CRTS Ⅲ板式轨道结构运营期间的养护维修提供相应技术支撑并为板式轨道充填层材料的发展提供理论依据。