中文摘要：

首先，确定轮载分布图、道床变形模量-荷载作用次数关系曲线和道床塑性累积变形百分率-荷载作用次数关系曲线；其次，利用有限元模型、变形模量-荷载作用次数关系曲线和塑性累积变形百分率-荷载作用次数关系曲线得出了随机荷载作用下轨道塑性累积变形随线路里程的变化图和道床塑性累积变形随荷载作用次数的变化图；最后，给出道床顶面和深度方向的垂向应力分布图和道床密实度与变形模量的关系曲线，并讨论了道床顶面应力和轨枕下垂向应力的分布及其与位移的关系，分析了道床密实度和变形模量之间的关系．结果证明，荷载大小和作用次数及其密实度是引起道床变形的重要因素．

英文摘要：

This paper first presents curves of wheel load distribution, ballast modulus-load number and plastic accumulative deformation percentage-load number of track bed, and then a general model of the ballasted track built up by finite element method（FEM）. Based on the FEM model and the abovementioned curves, the general displacement of the track was derived. The paper also presents figures of plastic accumulative deflection distribution of the track along the railway line under random load and plastic accumulative deflection of track bed-load number, and vertical stress distribution figures on the top of track bed and under sleepers and the curve of density-modulus for track bed. A discussion was held on the stress on the top of track bed and vertical stress distribution under sleepers and the relationship of stress of track bed with displacement. An analysis is made of the relationship of density with the modulus d track bed. The paper shows the load level, load number and density are important to settlement of track bed.