The Methods To Increase The Elasticity Of Ballast Track And Their Inflence On The Mechanical Properties Of Ballast Track

Ballast track is widely used in the high-speed railway at and below 250km/h in our country.However,the current high-speed railway ballast track exists the problem of lacking adequate elasticity on the bridge,tunnel,curve and other rigid basis,which greatly increases the rate of ballast pulverization and shortens the maintenance cycle of ballast bed.According to incomplete statistics,more than 90%of the settlement of ballast track is caused by the subsidence of ballast bed,and 80%of maintenance work of ballast track is around renovating ballast bed or other ballast track problems caused by ballast bed problems.Therefore,it is a very practical and significant work to systematic and comprehensive study the methods and their effects of increasing the elasticity of ballast track.The vibration and pressure are the most important factors leading to the pulverization of ballast.Now the commonly used methods of increasing the elasticity of ballast track is using elastic sleeper,composite sleeper and under ballast mat.Based on the abaove-mentioned methods,a finite element analysis model of ballast track with five kinds of parameters which simulates ? concrete sleeper track,elastic sleeper track,composite sleeper track,elastic sleeper + under ballast mat track and composite sleeper + under ballast mat track is established in this paper.The main works and the main conclusions about this paper are as following:1.The mechanical analysis model of ballast track is established,and the calculation method and results of parameters of elastic sleeper,composite sleeper and under ballast mat in this model are given.2.The law of acceleration transmission and dynamic pressure transmission of different track components in the frequency domain is studied with the method of harmonic response analysis.And based on the same method,the corresponding and effective methods reducing vibration and pressure are propounded for different frequency bands of different parts of ballast track.3.The influence of under ballast mat stiffness on the law of acceleration transmission and dynamic pressure transmission of elastic sleeper track and composite sleeper track is analyzed.And the suitable stiffness of under ballast mat for the high-speed ballast railway,which proposed to be 60MPa/m?150 MPa/m,is given.The above studies show that:overall,elastic sleeper,composite sleeper and under ballast mat can reduce the vibration and pressure of ballast bed.But the different methods have the different effect on the vibration and pressure reduction of different track components in the different frequency bands.That is,different method increasing track elasticity should be adopted to reduce the vibration and pressure of different track components in the different frequency bands.The stiffness of under ballast mat is not always the smaller the better,and it is suggested that the stiffness of under ballast mat is 60MPa/m?150 MPa/m according to the calculation of this paper and the relevant standards of foreign countries.