埋入式桩板路基粗颗粒夹层结构应力波传播及动力流固耦合效应研究

Embedded pile-board structure subgrade is widely applied in high-speed railway due to its good effect in the control of post-construction settlement. But the complex work environment, the long-term effects of the dynamic loads and natural force in the high cycle frequency trains, there will be the structural properties of degenerate , consequently , it makes some affect to the safety operators of high-speed railway . To this end, the paper is specification of research target key with embedded pile-board structure subgrade, through field investigation, model tests, theoretical analysis and numerical experiments, based on the theory of wave analysis in porous media, it constructs physical analysis model of coarse particles sandwich structure in the process of stress wave in order to reveal the stress wave propagation and development law of coarse particle medium, fluid-solid coupling mechanism and dynamic failure mechanism of coarse particles sandwich structure when train is under multi-cycle dynamic loads. building the dynamic fluid-solid coupling simulation platform with independent intellectual property rights of coarse particles sandwich structure, setting up the dynamical evolution mode of micro particle motion and macro accumulated deformation about coarse particles sandwich structure. Furthermore, the long-term stability quantitative evaluation method and prediction models of coarse particles sandwich structure would be constructed, the failure mechanism of dynamic damage and impact cyclical caused by rigid component would be revealed, and the vulnerability assessment model of coarse particles sandwich structure would be constructed. Based on this, it would provide theoretical guidance for the safty operation and maintenance of high-speed railway, and would provide a strong theoretical support for high-speed railway to achieve long-term development objectives.

埋入式桩板路基以其控制工后沉降的良好效果大量应用于高速铁路。但其工作环境复杂，在高周频列车动荷载和自然营力的长期作用下，会出现结构性能蜕化，影响高速铁路运营安全。为此，以埋入式桩板路基为研究对象，通过现场调查、模型试验、理论分析和数值试验等手段，基于多孔介质波动分析理论，构建粗颗粒夹层结构应力波传播过程的物理分析模型，揭示夹层结构状态对粗颗粒介质中应力波传播的影响；研究粗颗粒夹层结构在列车荷载多点、循环动态激振作用下的流固耦合机制，搭建具有自主知识产权的粗颗粒夹层结构动力流固耦合仿真平台；建立粗颗粒夹层结构微观颗粒运动、宏观累积变形的动力演化模式，提出粗颗粒夹层结构长期稳定性的定量评价方法和预测模型，揭示两侧刚性构件对粗颗粒夹层结构的动力损伤和循环冲击破坏机理。研究成果可为高速铁路的安全运营和养护维修提供理论指导，为高速铁路实现中长期发展目标提供强有力的理论支撑。

埋入式桩板结构路基粗颗粒夹层是一个软弱夹层，在高周频列车动荷载和自然营力的长期作用下，粗颗粒夹层的力学特征及动力流固耦合行为与其长期动力稳定性密切相关。本项目通过静动大型三轴试验，揭示了粗颗粒夹层填料在不同条件下的强度和变形特性，获得了考虑含水率、荷载作用次数、动应力水平相互耦合作用的累积变形预测模型。构建了应力波在板式无砟轨道结构-粗颗粒夹层-刚性地基界面效应模型，获得了饱和粗颗粒夹层结构对应力波在埋入式桩板路基传播的影响。建立了车辆-无砟轨道-饱和粗颗粒夹层-刚性地基耦合系统计算模型，获得了高速列车下饱和粗颗粒夹层结构的动力流固耦合响应，揭示了饱和粗颗粒夹层细颗粒损失的机理。建立了刚性地基下高速铁路路基级配碎石夹层的大比例模型试验，获得了最优含水状态和含水饱和状态下级配碎石夹层结构振动特性，揭示了其长期性能劣化的演变规律与机制。通过埋入式桩板路基原位加载试验，获得了埋入式桩板式路基粗颗粒夹层的瞬时振动特性和长期动力稳定性。研究成果可为高速铁路的安全运营和养护维修提供科学依据，具有重要的理论价值和实践意义。