基于离散元-有限元耦合模型的铁路有碴道床动力特性分析

Railway ballasted track mainly consists of sleeper, ballast bed and subgrade. Under repeated train loadings, ballast bed performs non-uniform settlement and reduction of elasticity, influencing the regularity and stability of the track. This project aims to study the dynamic behaviors of railway ballast bed based on the coupled discrete-continuous approach, considering the coexistence of discrete ballast and continuous sleeper and subgrade in the track. The overlapping-bonding approach is adopted to construct irregular, breakable ballast particles first and corresponding failure criteria is developed. Combing the discrete element method (DEM) and the finite element method (FEM), the DEM-FEM model is developed next for the interaction of discrete ballast and other continuous structures. Finally, the non-uniform settlement of ballast bed, the effect of the installation of geogrid and dynamic stiffness in the ballasted-ballastless transition zone of high speed railway track are studied based on the developed DEM-FEM method. This project helps reveal the dynamic behaviors of ballast bed under repeated train loadings, and provide a theoretical basis for the enhancement and reasonable design of railway ballasted track.

铁路有碴轨道主要由轨枕、有碴道床和路基等组成，其在往复列车荷载作用下会出现不均匀沉降、弹性降低等问题，严重影响轨道结构的平顺性和稳定性。针对有碴轨道中离散道碴颗粒与轨枕、路基等连续介质共存的结构特点，可通过发展离散介质与连续体模型耦合的数值方法对有碴道床的动力特性进行数值分析和试验验证。为此，本项目首先针对道碴颗粒的几何形态和破碎特性，采用镶嵌-粘结组合颗粒单元构造非规则、可破碎的道碴颗粒并建立粘接颗粒间的破坏准则；将离散元法与有限元法相结合，建立散体和连续体相互作用的DEM-FEM耦合模型和求解方法；对有碴道床的非均匀沉降、土工格栅加固和高速铁路有碴-无碴过渡段动刚度等典型问题进行DEM-FEM耦合分析，以揭示其动力特性演化的内在机理。本项目通过对铁路有碴道床动力特性分析的DEM-FEM耦合模型研究，有助于揭示其在往复荷载作用下的动力演变特性，为有碴轨道的改良措施和合理设计提供科学依据。

铁路有碴轨道主要由轨枕、有碴道床和路基等组成，其在往复列车荷载作用下会出现不均匀沉降、弹性降低等问题，严重影响轨道结构的平顺性和稳定性。针对有碴轨道中离散道碴颗粒与轨枕、路基等连续介质共存的结构特点，本项目发展了离散介质与连续体模型耦合的数值方法对有碴道床的动力特性进行数值分析和试验验证。针对道碴颗粒的非规则几何形态和破碎特性，采用镶嵌-粘结组合颗粒单元构造了非规则、可破碎的道碴颗粒并建立粘接颗粒间的破坏准则；将离散元法与有限元法相结合，建立了散体和连续体相互作用的DEM-FEM耦合模型和求解方法；对有碴道床的非均匀沉降、土工格栅加固和高速铁路有碴-无碴过渡段动刚度等典型问题进行了DEM-FEM耦合分析，揭示了其动力特性演化的内在机理。本项目通过对铁路有碴道床动力特性分析的DEM-FEM耦合模型研究，揭示了其在往复荷载作用下的动力演变特性，为有碴轨道的改良措施和合理设计提供了有力的科学依据。