高速铁路无砟轨道基床接触层水动力特征与颗粒迁移效应研究

The working condition of weak contact layer between rigid structure of ballastless track and flexible medium of granular at surface layer of subgrade is complicated. Contact state of ballastless track subgrade deteriorates under the long effect of high circular frequency dynamic train load and infiltration of surface water and other engineering factors, which affects the operation safety of high speed railway. Therefore, through the means of site investigation, model test, numerical calculation and theoretical analysis, and taking the contact layer as the research object, pore-pressure calculation model of contact layer under multi-physics coupling is constructed based on porous media percolation theory, revealing the formation mechanism of high pore-pressure and driving mechanism of migration of fine particles. The fluid-solid coupling mechanism on graded aggregate of contact layer under dynamic cycle vibration action of train load is researched to build microscopic fluid-solid coupling simulation platform of the pore-pressure and particle migration, revealing the mechanism of subgrade mud pumping. Dynamic analysis model reflecting different layer damage of ballastless track subgrade coupling system is established, revealing degradation mechanism of dynamic performance of contact layer under the condition of particle migration. Evaluation method and analysis model on the long-term stability of ballastless track subgrade contact layer are established. The research results can provide theoretical support for the construction, maintenance and repair technology of ballastless track subgrade engineering of high-speed railway.

高速铁路无砟轨道刚性结构与基床表层散粒体柔性介质接触层较为薄弱，服役环境复杂，在高周频列车动荷载和入渗表水等工程因素的长期作用下，无砟轨道-基床接触状态易致劣化，影响高速铁路运营安全。为此，以高速铁路无砟轨道基床散粒体接触层为研究对象，通过现场勘察、模型试验、理论分析和数值计算等手段，基于多孔介质渗流理论，构建多场耦合作用下接触层孔压计算模型，揭示接触层高孔压形成机理及对细颗粒迁移的驱动机制；研究接触层级配碎石在列车荷载循环动态激振作用下的流固耦合机制，搭建孔压-颗粒迁移细观流固耦合仿真平台，揭示基床翻浆病害机理；建立反映不同层间损伤状态的无砟轨道-路基耦合系统动力分析模型，揭示颗粒迁移环境下无砟轨道基床层间动力性能蜕化机制，构建无砟轨道基床接触层结构长期稳定性评价方法与分析模型。研究成果可为高速铁路无砟轨道路基工程的建设、养护维修技术提供理论支撑。

高速铁路无砟轨道刚性结构与基床表层散粒体柔性介质接触层较为薄弱，在高周频列车动荷载和入渗表水等工程因素的长期作用下，无砟轨道基床接触状态易发生劣化，产生翻浆、脱空等病害，严重影响高速铁路运营安全。本项目在级配碎石渗透稳定性试验以及静动大型三轴试验的基础上，建立了车辆-无砟轨道-饱和路基系统计算模型，研究了列车荷载下饱和基床表层动力流固耦合响应，揭示了复杂应力条件下级配碎石接触层高孔压形成机理，提出了列车荷载下饱和基床表层细颗粒水力损伤机制；研究了流固耦合作用下基床表层级配碎石细颗粒损失动态发展过程，揭示了无砟轨道基床翻浆产生机理。建立了无砟轨道路基翻浆室内足尺模型试验，揭示了基床翻浆病害发展的三个阶段，获得了无砟轨道路基接触层长期性能劣化的演变规律与机制；通过现场行车实验，获得了基床翻浆条件下无砟轨道路基动力特性的变化规律。建立了反映不同层间损伤的路基-板式无砟轨道-车辆耦合空间分析模型，获得了基床翻浆致界面不同损伤对无砟轨道路基动力性能的影响，揭示了基床翻浆环境下无砟轨道基床层间动力性能的蜕化机制，构建了无砟轨道基床接触层结构劣化等级定量评定方法与分析模型。研究成果可为高速铁路无砟轨道路基结构健康服役和养护维修提供重要理论支撑。