桥墩沉降引发无砟轨道层状结构非协调变形机制及其对高速列车行车性能的影响

高速铁路运营中会出现大面积桥墩不均匀沉降现象，造成无砟轨道变形及力学性能劣化，导致轮轨接触异常，威胁列车安全平稳运行。本项目拟针对连续多桥墩不均匀沉降下无砟轨道层间相互作用的演变规律及时－空不均匀分布特性、轨道非协调变形机制等关键科学问题开展理论与试验研究。首先，基于内聚力理论研究无砟轨道层间粘结力与张开位移的非线性关系，结合室内试验，构建轨道层间非线性粘结本构关系；然后，基于列车―轨道―桥梁动力相互作用理论，建立考虑多墩沉降和无砟轨道层间粘结特性的高速车轨桥耦合动力学模型；在此基础上，研究多墩沉降下轨道各层结构变形过程及层间力重分布特性，探明轨道变形与层间力分布之间的内禀关系，揭示多墩沉降下无砟轨道非协调变形机制；最后，研究高速列车通过桥墩沉降区域时的动态特性，掌握多墩沉降对高速轮轨非线性耦合振动行为和列车运行安全平稳性的影响。研究成果可为桥墩沉降区域轨道和桥梁的运维管理提供理论依据。

With the long-term operation of high-speed railways, multi-pier settlement occurs unavoidably, which induces track deformation and degradation of track property. Further, the wheel-rail vibrations are aggravated, threatening the running safety of high-speed trains. Focusing on the scientific problems of pier settlement induced evolvement of interlamination interaction, distribution characteristic of interlamination force, and mechanism of track inconsistent deformation, the following investigations are conducted in this project. Primarily, the nonlinear relationship between interlamination force and crack size is investigated based on the cohesion theory. Combined with a designed laboratory test, the constitutive relation between concrete structure and CA mortar is obtained. Then a high-speed train-track-bridge dynamic model considering multi-pier settlement and nonlinear interlamination adhesive property is established based on the train-track-bridge dynamic interaction theory. Adopting the model, the process of track deformation and redistribution of interlamination force are studied to reveal the mechanism of inconsistent deformation of ballastless track. Finally, the dynamic performance of high-speed train running through settlement areas is investigated to grasp the wheel-rail nonlinear vibration characteristic and train dynamic performance. The research achievements provide theoretical foundation for operation and maintenance management of the ballastless track and bridge structures with pier settlement.