摘要：研究目的：目前，有砟-无砟轨道过渡段轨下刚度的设置仅考虑施工便利性，线路动不平顺性未得到根 治，仍存在较多的线路病害。为解决上述问题，需要研究有砟-无砟轨道过渡段的轨下刚度与动不平顺的关 系，从而制定合理的过渡段过渡方式，达到减少线路维修、提高乘车舒适性的目的。研究结论：通过分析线路动不平顺的动不平顺线形、钢轨挠度变化率、线路动不平顺二次导等指标，得出 以下结论：(1)现有有砟-无砟轨道过渡段的设置未完全解决线路轮轨力增值过大、行车平顺性差等问题； (2)良好的过渡段轨下刚度线形设计可显著改善线路过渡效果，建议采用线性过渡方案;若过渡段采用分段 式过渡，过渡段分段数不得少于5段;过渡段的长度宜结合车速设置为20 ~ 30 m;(3)合理的轨下刚度设置方 式可有效降低高速、重载线路有砟-无砟轨道过渡段病害问题，并可为其他过渡段设置提供参考。

Abstract ： Research purposes ： At present，when designing the track stiffnes at tlie transition zones of baiasted track and baisastless track，only the convenience of construction has been considered. There are still many diseases of railway line caused by the dynamic irregularity of railway line. In order to solve these diseases，we need to study the characteristics of dynamic irregularity at transition zones of ballasted track and ballsastless track. Based on this， it can develop a reasonable transition schemes to achieve the purpose of reducing line maintenance and improving the safety and comfort to the passengers. Research conclusions ： From the evaluation indexes of dynamic irregularity linear type，rail deflection rate，rail vibration acceleration，wheel/rail force，the conclusions are obtained as follows： (1) The problems of excessive wheel rail force and bad smooth lines still exist at the transition zones of ballasted track and ballsastless track. (2) Favorable design of track stiffness at the transition section can significantly improve the transition effect. The analysis results showthat the most suitable design is linear transition，and the transition effect is very good when the quantity of transition segments is no less than 5. The setting length of transition zones should be 20 ?30m，and particular length of specific transition zones should be according to the driving speed. (3) The reasonable design of rail stiffness at the transition zones of ballasted track and ballsastless track can effectively reduce the diseases in high speed and heavy load line，which also can provide references for otlier transition zones.