Exprimental Study On Low-frequency Vibration Control Of Floating Slab Tracks Based On Dynamic Vibration Absorbers

Recently,urban rail transit in China has been rapid development,the traffic networks of subway and light rail being formed quickly,so the congestion situation of urban traffic has been significantly alleviated,however,the environmental vibration caused by the operation of urban rail transit has increasingly become a prominent problem.Currently,floating slab track(FST)is the most effective form of vibration damping track,but it can cause the low-frequency vibration amplification at the natural frequency,which has a great influence on the precision instrument,building,human body and so on.In this thesis,focusing on the problem of the low frequency vibration amplification caused by FST and based on summarizing the vibration control measures of track structure at home and abroad,the experiments of dynamic excitation and wheel-drop impact are performed on the FST using dynamic vibration absorbers(DVAs)to study the effect of DVAs on the low-frequency vibration control of the FST,which proves the necessary basic research data for the application of DVAs on FST.Firstly,based on relevant literatures about all kinds of vibration damping tracks,commonly used technologies of attenuating vibrations in track structure are summarized at home and abroad,including vibration control measures on the rail,fastener,sleeper,and ballast bed,and the research status and problems to solved about the FSTs are summarized emphatically.Recently,the vibration damping effect of the FST is best among all kinds of vibration damping tracks,however,the low frequency vibration of the FST will be enlarged in the resonance zone.Then,referring to parameters of the typical FST in the laboratory,a three-dimensional finite element model of the FST is established,and the modal analysis of the FST has been carried out,combined with the modal test.According to the design methods of the FST-DVAs,the designed parameters of the DVAs used to control the vertical vibration modal of the FST is obtained,and the influence of the DVAs parameters on the low-frequency vibration control the FST has been analyzed,which is based on the vehicle-track vertical coupled model and the finite element of FST using the DVAs.Result shows that,with the increase of the mass ration of the DVAs,the effect of the DVAs on the low-frequency vibration control of the FST increases at the natural frequency.When the stiffness and damping parameters of the DVAs are deviated from the optimal value,the vibration of the FST is enlarged in the frequency band nearby the natural frequency and the vibration amplification becomes more obvious with the increase of the parameter deviation.Finally,according to the design parameters of the DVAs,the device of the DVAs is manufactured and installed on the FST in the laboratory.With the loading equipment in the laboratory,the experiments of dynamic excitation and wheel-drop impact are performed on the FST using dynamic vibration absorbers(DVAs)to study the effect of DVAs on the low-frequency vibration control of the FST under sinusoidal steady excitation and the impact load.Results show that,under sinusoidal steady excitation,the peak values of the vibration acceleration and displacement of the FST using the DVAs are obviously lower than that of the FST without the DVAs in the resonance region and the vibration acceleration peak of the bearing base is obviously reduced.Such as when the mass ratio of the DVAs is 0.3,at the first natural frequency of 10Hz,the insertion loss of the slap is 13.9dB and the insertion loss of the bearing base is 12.5dB.Under the wheel-drop impact,the DVAs not only control the vertical translation of the FST,but have a significant inhibitory action on the first-order vertical bending.