温度荷载与列车反复作用下混凝土-水泥乳化沥青砂浆界面疲劳损伤机理

The bonding interface of concrete and cement emulsified asphalt mortar has been widely used in the continuous slab ballastless track in high-speed railway in China. However, the debonding and crack of some interfaces cause the upward deformation of slab track, which directly affects the safe operation of high-speed train. This research project focuses on the fatigue performance and damage mechanism of the slab track’s interface which is under the repeated actions of temperature load and train. The research contents include: Based on the measured data of the track structure’s temperature, the load spectrums considering the coupling effect of temperature and live load are established. On this basis, the interface fatigue fracture tests are carried out. The evolution law of interface fatigue stress as well as the interface failure pattern are obtained by the digital image correlation technology. Then, the degradation model of interface shear and tensile cohesive strength can be established. Afterwards, the multi-scale numerical model of concrete to mortar interface which is used to realize the virtual simulation of the interface’s damage and failure processes should be established. And the influence of repeated actions of temperature load and train on the interfacial crack behaviour can be clarified. Eventually, based on the mechanism of interfacial crack produce and propagation, the interface fatigue life prediction model is established. Thus, the interface safety under repeated actions can be reasonably estimated. The research results can provide an important reference for the reinforcement and fatigue resistance design of continuous slab ballastless track's interface.

混凝土与水泥乳化沥青砂浆界面广泛存在于我国高速铁路纵连板式无砟轨道结构中，但使用过程中部分界面的脱黏及开裂导致轨道板上拱，影响高速列车的安全运营。本课题聚焦于该类无砟轨道结构界面在温度荷载与列车反复作用下的疲劳性能与损伤机制，开展以下研究：基于轨道结构温度实测数据，编制考虑温度荷载与列车活载组合效应的典型载荷谱；在此基础上，开展界面疲劳断裂试验，利用数字图像相关技术，研究界面疲劳应力演化规律和界面破坏形态，建立界面剪切和拉伸粘结力的强度退化模型；基于细观力学理论，构建混凝土-砂浆界面多尺度计算模型，实现界面疲劳损伤和破坏全过程的虚拟仿真，明确温度荷载与列车反复作用对混凝土与砂浆界面疲劳开裂行为的影响；基于界面裂纹萌生与扩展机制，建立界面疲劳寿命预测模型，对界面在反复荷载作用下的安全性进行合理评估。本课题的研究成果可为纵连板式无砟轨道界面裂缝的维修加固与抗疲劳设计提供重要参考。

纵连板式无砟轨道，又称为CRTS Ⅱ型无砟轨道，广泛应用于我国高速铁路系统，但实际工程中发现混凝土轨道板与水泥乳化沥青砂浆(简称CA砂浆)之间容易发生界面脱黏，造成轨道板和无缝线路形位变化，影响高速列车的运营安全。因此，明确复杂荷载作用下混凝土与砂浆界面两相材料之间的黏结强度与脱黏失效机制对纵连板式无砟轨道力学行为分析及维修养护至关重要。本项目首先基于温度场长期监测数据，建立了桥梁-无砟轨道结构温度分布数据驱动模型，为后续界面静力与疲劳试验加载方案的制定提供了依据；进一步的，开展了混凝土-CA砂浆界面单剪试验与劈拉试验，研究了界面剪切和拉伸黏结性能，获得了两种受力状态下界面破坏特征与模式、界面破坏荷载、极限强度、断裂能与开裂模式；另外，开展了混凝土-CA砂浆界面剪切与劈拉疲劳试验，揭示了界面疲劳破坏特征，研究了不同应力幅值作用下的界面疲劳寿命及疲劳裂纹发展规律，分别建立了界面在剪切和拉伸受力状态下的应力-寿命(S~N)曲线；基于近场动力学，实现了混凝土与砂浆界面的剪切破坏与拉伸破坏的全过程虚拟仿真，研究表明近场动力学方法能较真实模拟出界面断裂过程；提出了混凝土-CA砂浆界面剪切黏结-滑移模型和界面竖向拉伸黏结力强度模型，并结合试验结果给出了具体参数建议值；最后，本项目建立了桥梁-纵连板式无砟轨道一体化有限元模型，探讨和评价了界面黏结状态对梁轨结构系统受力性能的影响。本项目研究成果填补了混凝土-CA砂浆界面黏结强度模型的空缺，可为纵连板式无砟轨道界面裂缝的长期维修加固提供重要参考。