Analysis Of Dynamic Characteristics Of Track Structure In CRTSⅡ Slab Track TCDS Under Differential Settlement

The construction of the Beijing-Shanghai high-speed railway is of great significance to the development of China’s railway and economy.At the transition section of the subgrade and bridge,the stability of the track structure is maintained by setting the anchoring structure at the rear end of the bridge platform.However,the long-term load of the train caused differential settlement of the subgrade,which exacerbated the problem of track irregularities.With the perspective of dynamics,the effect of differential settlement on the dynamic response of track structure in terminal displacement configuration system(TDCS)is explored,and the recommendations for the settlement limit of the roadbed are provided to provide a theoretical basis for the improvement of track smoothness.The main research work of the paper is as follows:(1)First of all,based on the development of ballastless orbits at home and abroad the current status of the research on the structure of TDCS.Taking the anchorage system of ballastless track on Beijing-Shanghai high-speed railway as the research object,a vehicle-track rigid-flexible coupling model of CRTSⅡ slab track rail TCDS based on finite element method and multibody dynamics theory.(2)Secondly,the vertical coupling dynamics model is used to analyze the vertical deformation characteristics of the track at different settlement positions under the action of a typical roadbed settlement of 20 mm/20 m and determine the most unfavorable position in the settlement area.On this basis,the influence of different driving speeds and track structure design parameters on the dynamic performance of ballastless tracks is analyzed,and the speed limit and design parameter values under subgrade settlement conditions are determined.Research indicates that In the case of subgrade settlement of 20 mm/20 m,when the train passes the differential subsidence section of TCDS,at the place where the maximum settlement of the subgrade occurs,the structure is in the most vulnerable position and should be paid attention to.When the train speed reaches 350 km/h,the vehicle safety indicators are within the limits.The vertical acceleration of the vehicle body is greater than the limit,which affects passenger comfort.The dynamic response values of each structural layer of the system are also relatively large.The recommended speed range is within 300 km/h.(3)Finally,analyze the influence of the differential settlement parameters of the train on the dynamic response of each structural layer of the ballast track in the end barbed area.Compared vertical dynamic performance of track structure with subgrade settlement amplitude and wavelength.Based on dynamic safety evaluation indicators and train smoothness and riding comfort indicators to propose subgrade settlement limit recommendations.And compared the dynamic performance of the track structure with that of the subgrade without differential settlement.Research indicates that With the increase of the settlement amplitude and the settlement wavelength,the influence of subgrade settlement amplitude changes on the system dynamic response shows a linear increase trend,and the effect of subgrade settlement wavelength changes on the system dynamic response shows a non-linear trend.Recommended subgrade settlement limit value 20 mm / 20 m.Compared with when the roadbed does not settle,the vertical displacement of each structural layer increases by 23% to 34%,and the vertical acceleration increases by 1.5 to 2.3 times the original.Subgrade settlement should be monitored in a timely manner to ensure the stability of line conditions and driving safety.