Several improvements of accuracy and computational cost of 3-D elastoplastic FEM for simulating railway ballast settlement

本文采用三维有限元法模拟了铁路有碴轨道的沉降现象。采用时域均匀化方法、多时间尺度方法和循环密实化模型，降低了三维道碴沉降分析的计算成本。采用粒子群优化算法对扩展子加载面弹塑性模型的材料参数进行了识别。采用一次二阶矩法建立了模拟材料参数随机性引起的道碴沉降变化的数值方法。

In the present study, settlement phenomena of a railway ballasted track are simulated with 3-D FEM. Computational cost of 3-D ballast settlement analysis is reduced using a time-domain homogenization method, a multi-time scaling method or a cyclic densification model. The material parameters for the extended subloading surface elastoplasticity model are identified using the particle swarm optimization(PSO). The numerical method for simulating the variation of ballast settlement caused by the randomness of material parameters is developed with the first-order second-moment method(FOSM).