中文摘要：

通过2．5维有限元结合薄层单元方法，建立了列车运行荷载作用下轨道和地基动力相互作用的3维分析模型，求解不同运行速度列车荷载作用下路堤下卧层地基中动偏应力的分布，结合软黏土在循环荷载作用下的累积塑性应变理论，建立了路堤下卧层地基在列车运行荷载作用下长期动力附加沉降的计算方法。在此基础上采用瑞典X2000高速列车的实际轨道和地基情况进行了计算，分析了长期沉降随时间的发展过程及其在地基中的分布规律，特别是考虑了列车运行速度对路基沉降的影响。

英文摘要：

A dynamic coupling model of track structure and underlying ground under moving load action is developed by employing the 2.5 dimensional finite element method together with thin layer element method. First, the distribution of dynamic stress in ground due to train traffic loadings at different speeds is computed; then, incorporating Li and Selig＇s Method （1996）, a computation procedure to evaluate long-term settlement of subgrade ground is proposed. The Swedish high-speed railway X-2 000 running on soft ground in the West Coast is introduced as an illustrative case study to demonstrate the development of long-term settlements with time and its distribution inside ground. Also a parametric study is conducted to consider to influence of train＇s running speed on long-term settlement in soft soil ground.