铁路道床有砟-无砟过渡段动力特性的DEM-FEM耦合分析

针对铁路道床有砟-无砟过渡段的结构特点,采用离散元-有限元耦合模型分析散体道砟和无砟道床间过渡段的动力特性。散体道砟道床和无砟道床分别采用离散元方法 DEM和有限元方法 FEM模拟,而在过渡段将道砟颗粒嵌入无砟道床以增加道砟颗粒与无砟道床间的咬合力,并在离散元和有限元耦合区域实现了力学参数的传递。采用以上DEM-FEM耦合方法对有砟-无砟道床及其过渡段在列车荷载作用下的沉降过程进行了数值分析。计算结果表明,离散元方法中道砟颗粒间的力链呈现非对称梯形分布,其与有限元方法中的应力分布趋势一致;采用嵌入式道砟颗粒的方法可以增加有砟-无砟过渡段道砟间的咬合力,有效约束道砟颗粒的位移,减少有砟-无砟道床间的沉降差异。本文计算模型可以合理地分析有砟道床的力链分布以及无砟道床的应力分布,确定列车荷载下道床有砟-无砟过渡段的动力学行为。

Dynamic behaviors of transition zone between ballasted and ballastless tracks analyzed with coupled DEM-FEM method

According to the structural characteristics of the ballasted-ballastless transition zone of railway track,this paper presents a coupled discrete-finite element method to simulate its dynamic behavior.The discrete element method (DEM) and the finite element method (FEM) are employed to model the ballast bed and ballastless track slab,respectively.In the transition zone between ballasted and ballastless tracks,the ballast particles are embedded into the slab to increase the inter-lock effect.A coupling algorithm is proposed in the DEM-FEM coupled region to transfer the mechanical parameters between DEM and FEM domains.With this DEM-FEM coupled method,the settlement process of ballasted track,ballastless track and their transition zone are simulated under the cyclic loads of train.The force chain distribution of ballast particles simulated with DEM appears like an asymmetrical trapezoid,which matches the stress distribution in the slab simulated with FEM.The embedded method of ballasts into slab can constrain the displacement of ballast and reduce the differential settlement in the transition zone.The coupled DEM-FEM method can be applied to investigate the dynamic behavior of transition zone under high-speed train loading.