| With the increase of the train running speed,the requirements on the smoothness of the rails have become more and more strict.Since the engineering properties of embankments and bridges are quite different,serious unevenness is prone to occur in the linking of embankments and bridges.On the basis of consulting the relative domestic and overseas technical materials,this paper conducts theoretical analysis and engineering test studies to the dynamic performance of the bridge/approach embankment on high-speed railway as per the deformation occurrences of the bridge/approach embankment and the features of vehicle-track interaction.1. Calculation,Analysis and Assessment of the Dynamic Performance of the Bridge/Approach Embankment on High-Speed RailwayThis paper has comprehensively analyzed the effect patterns of the factors such as the bending deformation of the rail top,the rigidity change of the rail foundation,the train running speeds,the train running direction and other factors on the dynamic performance of the bridge/approach embankment of high-speed railway for the first time in China.The calculation results have demonstrated that the rail top bending deformation resulted by the settlement difference of the embankment and bridge is the main factor that effects the safe and comfortable running of high speed trains,the handling of which should be emphasized;the rigidity changes of the track foundations resulting from the rigidity differences between the embankment and bridge should not become the control conditions.The changes in the indexes of dynamics performance are not big when trains pass through the bridge/approach embankment of high-speed railway and the running direction of trains will not play a restricting role.Taking the control values of dynamics performance assessment indexes preliminarily established by this paper as the target function,the unevenness control standards(rail top bending angle)of the bridge/approach embankment under different speed grades are:V=160km/h, θ≤5.5‰ , V=250km/h, θ≤3‰ ,V=350km/h.1.5 ,which are very good because they tally with the relative Japanese research results.2. Structure Designs and Technical Standards of the Bridge/Approach Embankment on High-Speed RailwayThis paper has put forth the structure designs and technical standards for the bridge/approach embankment under different speeds in light of the analysis results of the dynamic performances of the bridge/approach embankment by the relative domestic and overseas materials about the treatment measures for the bridge/approach embankment and the practical experience and research results of the existing projects;part of the contents of which have been put into the"Temporary Requirements for Design of Railways, Bridges, Tunnels and Stations of Newly Built Express Railways -with 200km/h Trains"and the" Temporary Requirements for Design of Railways, Bridges,Tunnels and Stations of the Beijing-Shanghai High-Speed Railway",which has been applied in the construction of the Qinhuangdao-Shenyang dedicated passenger line and the engineering effects of which are being tested by its operation.3. Tests and Study on the Deformation Properties of Geogrid-Reinforced GravelThe seven groups of large scale model tests to change the laying separation interval of geogrid and the compact density of gravel have been conducted in a rigid model box with the sizes of length l.Omxwidth l.Omxheight 1.0m that measured and tested the longitudinal loads and deformation curves of the geogrid-reinforced gravel samples under the actions of different lateral pressures(It was the first time for the lateral load-on technology by flexible pocket of water to be used in China).The test results have demonstrated that the laying of geogrid can significantly reduce the deformation of the gravel samples under the actions of the longitudinal loads.the effects of which are inversely proportional to the laying separation interval of geogrid;the deformation of the gravel samples under the actions of longitudinal loads can be significantly decre...
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