Study On High Frequency Vibration Of Urban Elevated Track Structure And Its Influence On Transmission Characteristics

With the rapid development of our urban rail transit,it has effectively alleviated people’s traffic pressure,but also brought a series of negative problems,especially the vibration problem is the most prominent,vibration will cause environmental problems and vehicle running quality problems,the root cause is the wheel-rail system vibration caused by irregular wheel-rail.On the basis of summarizing the previous research results,and aiming at the measured data of short-wave irregularity of rail surface of some urban rail surface of some urban rail transit lines,this paper establishes the coupled vehicle-rail-bridge vibration analysis model in frequency domain,and analyzes the influence of short-wave irregularity of rail surface on the vibration response of elevated rail structure,as well as the distribution and attenuation law of vibration energy in elevated rail structure from the perspective of frequency domain.The main research content of this paper is as follows:1.Based on the measured data of short wave irregularity of Shanghai Railway Line 11,the data are preprocessed firstly,including the elimination of outliers,the elimination of trend term and the stationarity test.Then the spatial distribution characteristics of short wave irregularity of the rail are analyzed from the aspects of waveform and time frequency.The power spectrum of short wave irregularity of the rail is estimated and analyzed by the improved covariance method in modern spectral estimation.2.According to the characteristics of urban elevated track structure,the vibration frequency domain model of three-layer beam with finite length discrete support was established.Based on the wheel-rail contact theory,the coupling vibration analysis model of vehicle-railbridge system under the action of track irregularity was established.Virtual excitation method was used to solve the analysis model.3.Based on the established coupling vibration analysis model of vehicle-rail-bridge system,the influence of different track irregularity states of urban rail transit on the vibration level distribution of elevated rail structure is analyzed from the perspective of frequency domain.The results show that the amplitude energy of wheel and rail force and the vibration level of rail and rail plate increase with the deterioration of short wave irregularity of rail surface.The short wave irregularity of the rail surface in the welded joint area has the greatest influence on the vibration acceleration response of the car body.4.Based on the power flow theory,the vibration transmission characteristics of the elevated rail structure under the condition of short-wave irregular rail surface are analyzed by using the coupling vibration analysis model of vehicle-rail-bridge system,and the influence of rail structure parameters on the vibration transmission characteristics of the elevated rail structure is studied.The results show that using heavy rail can reduce the high frequency vibration level of rail,and reducing the stiffness of sleeper cushion can reduce the vibration level of bridge structure,which is helpful for vibration and noise reduction of structure.5.The finite element model of track box girder structure was established with ANSYS software,and the vibration characteristics of the structure were analyzed from the three aspects of natural vibration,time domain and frequency domain,and the vibration acceleration level was compared with the theoretical model.The results show that when the vibration frequency is greater than 60 Hz,the vibration form of box girder is mainly local vibration.The vibration level of box girder roof is higher than that of other track structure areas.The vibration form of roof and wing plate is mainly vertical vibration.