循环复杂荷载下无砟轨道界面疲劳起裂扩展机理与演变模型研究

The fatigue damage of ballastless tracks interface that continuously deteriorates the overall static and dynamic performance of track system is the bottleneck for keeping long-term safety service performance of high-speed ballastless tracks. This project deals with the key problem of fatigue initiation and propagation mechanisms and evolution model for interface cracks of ballastless tracks under cyclic complex loads, in reaction to the typical issue of interface fatigue failure of ballastless tracks. Based on the cohesive zone model and combined with fatigue damage and fracture method and experiments, a constitutive model for fatigue initiation and propagation of the interface crack of ballastless tracks is first established from the perspective of damage mechanism. Then, by using the method of combing the vehicle-track coupled dynamics, fluid-structure coupled vibration and thermodynamic theory, the characteristics of train dynamic load, interface hydrodynamic pressure, and temperature load that are applied to ballastless tracks will be investigated. Finally, the fatigue damage evolution model for the interface crack of ballastless tracks under complex loads will be developed to reveal the mechanisms of fatigue initiation and propagation of the interface crack, and to elucidate the damage evolution law during the entire failure process. Research achievements of the project will provide some theoretical foundation for condition-based maintenance and repair of ballastless tracks, and have some theoretical significance and engineering value for ensuring the long-term stable and healthy operation of high-speed railways with high safety, high reliability and high quality.

高速铁路无砟轨道界面疲劳损伤会导致结构的整体静动力学性能发生持续退化，是轨道系统保持长期安全服役性能的薄弱环节。本项目针对无砟轨道界面疲劳失效这一典型病害现象，围绕循环复杂荷载下无砟轨道界面疲劳起裂扩展机理与状态演变这一核心问题，以内聚力理论为基础，结合疲劳损伤、断裂力学方法与试验研究，首先从损伤机理上构建无砟轨道界面疲劳损伤起裂与扩展本构关系；再综合运用车辆-轨道耦合动力学、流固耦合振动与热力学理论，研究高速铁路无砟轨道列车动荷载、界面动水压力与温度荷载的作用特征；最后，建立循环复杂荷载下无砟轨道界面疲劳损伤状态演变分析模型，揭示无砟轨道界面疲劳起裂扩展机理、疲劳失效全过程状态演变规律，为制定无砟轨道状态维修策略提供一定的理论支撑，对有效地保障高速铁路高安全、高可靠、高品质的长期稳定健康运营具有良好的理论意义和工程价值。

本项目围绕循环复杂荷载下无砟轨道界面疲劳起裂扩展机理与状态演变问题，开展了无砟轨道界面疲劳损伤损伤本构关系理论与试验研究，高速列车动荷载、界面动水压力与温度荷载循环作用特征研究，循环复杂荷载下无砟轨道界面疲劳损伤演变分析模型与试验研究。项目通过开展单调荷载下界面法向和切向损伤开裂模拟试验，确定了无砟轨道界面粘结力与张开位移的非线性关系，获取了内聚力本构模型中的关键参数，提出了合理描述轨道界面损伤力学行为的内聚力准则；通过开展循环荷载下粘结构件界面疲劳损伤试验，建立了界面起裂损伤增量与循环荷载大小之间的关系，提出了基于疲劳内聚力本构关系的无砟轨道界面疲劳损伤分析模型。项目还建立了考虑轨道纵向振动和结构损伤的车轨耦合动力学分析模型和界面离缝动水压力计算模型，探明了高速车辆动载下无砟轨道离缝动水压力时空变化特性与界面粘结失效行为，揭示了界面离缝和轨道板裂纹状态对车轨系统动力响应的影响规律；建立了无砟轨道温度梯度变化计算模型，研究了长期服役期间轨道结构温度梯度度变化规律。在上述基础上，项目提出了无砟轨道界面疲劳损伤模型的数值实现方法与高效计算方法，实现了循环荷载下无砟轨道界面疲劳损伤非线性演变全过程分析；并基于无砟轨道动态性能演变实尺模型试验揭示了疲劳列车载荷作用下双块式无砟轨道力学特性演化规律。项目研究成果为高速铁路无砟轨道结构性能评估与科学运维提供了理论支撑与应用参考。