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方法对某铁路有碴轨道的沉降现象进行了数值模拟。为了减少三维道床沉降分析的计算量，采用了时间域均匀化方法、多时间尺度法或循环密实化模型。利用粒子群算法对扩展次加载面弹塑性模型的材料参数进行了辨识。采用一阶二阶矩方法，建立了模拟道床沉降量随材料参数随机性变化的数值方法。

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).