中文摘要：

我国众多铁路干线分布于深季节冻土地区。铁路路基土层的冻融状态随着季节的交替变化而改变,相应的列车行驶时引起的路基动应力分布也有所不同。考虑路基土体的参振效应,通过改进车辆-轨道-路基垂向耦合动力学模型获取不同季节列车行驶振动荷载时程,进而通过动力有限元数值模拟方法,研究季节变化对列车行驶引起的路基动应力分布规律的影响。研究表明：路基土中的动应力幅值及其沿路基深度的分布规律与该时期路基土的冻融状态密切相关,基于此结论,提出深季节冻土地区不同季节铁路冻土下限范围内路基动应力的简化计算方法。该研究对于优化季节性冻土地区铁路路基设计方法,完善路基长期动力稳定性能评价方法等具有重要意义。

英文摘要：

Many railways were constructed in regions of China that experience seasonal freezing and thawing cycles in subgrade soils.Consequently,the dynamic stress distribution in subgrade soils induced by passing trains was observed to vary in different seasons.The research first focused on the development of a vertical train-track-subgrade coupled dynamic model,which considered the vibration of soil layers and the time histories of loading.Second on the effect of seasonal variations on the dynamic stress in subgrade soils,which was conducted by FEM computational simulations.Based on the results,the dynamic stress distribution and amplitudes were closely related to the frozen or thaw states of the subgrade soil.Third on the development of a simplified method for calculating the dynamic stress in subgrade soils induced by passing trains,which could be used in railway subgrade designs in seasonal frozen regions.The achievements of this research will be useful for optimizing the subgrade design method and completing the evaluation method of the long-term stability of the subgrade soil.