针对有砟道床动力特性分析的嵌入式离散元-有限元耦合方法

在离散元-有限元耦合方法中,离散元和有限元交界面处的耦合方式对整体有砟道床的力学行为影响显著.采用基于球形单元的镶嵌单元或粘结单元模拟有砟道床时,由于球形单元和有限单元表面的自锁能力较差,使道砟层在列车载荷作用下容易产生侧向滑移,导致数值模型不稳定.此外,在实际铁路道床中,底部道砟均不同程度地嵌入路堤.为此,发展了一种嵌入式离散元-有限元耦合方法,通过设置一层嵌入地基有限元模型中的球形颗粒传递离散元域和有限元域间的力学参数,实现离散元和有限元方法的耦合.数值结果表明,嵌入式离散元-有限元耦合模型能够有效降低有砟道床的侧向位移,数值结果更加稳定,在处理与有砟道床类似的连续介质与散体介质的耦合问题时推荐采用嵌入式耦合算法.

An embedded discrete-finite element coupling method for dynamic analysis of ballast bed

The coupling mode at the interface between a discrete element and a finite element has a significant influence on the behavior of the whole ballast bed in the discrete-finite element method.In the simulation of ballast bed with a clump model or a bonded model,due to the poor self-locking capacity of spherical element and finite element surface,lateral slip of a ballast layer is easy to occur under a train load,resulting in instability of the numerical model.In addition,in a real railway bed,the bottom ballast is embedded in the embankment.Therefore,an embedded discrete-finite element coupling method is developed in this paper.By setting several spherical particles embedded in the embankment finite element model to transfer the mechanical parameters between the discrete element domain and the finite element domain,the coupling between discrete element and finite element methods is realized.Numerical results show that the embedded discrete element-finite element coupling model can effectively reduce the lateral displacement of the ballast bed,and the numerical results are more stable.It is recommended to use the embedded coupling algorithm to solve the coupling problem between continuous media and discrete media like a ballast bed.