| With the rapid development of rail transit technology,the problems of bridge vibration and noise induced by trains passing over the bridge becomes more and more prominent.The sound barriers can significantly block the spread of noise so they are widely used in railway lines.As the speed of vehicles increases,the wheel-rail excitation is enhanced,which causes the vibration of the bridge and the sound barrier on it to increase.At this time,the sound barrier and the bridge radiate noise around as a vibration source,thereby indirectly weakening the noise reduction effect of the sound barrier.In this thesis,a railway viaduct and its vertical sound barrier were taken as the engineering background.The distribution law and influencing factors of the vehicle-induced vibration of the bridge-sound barrier structure system were deeply studied.Finally some vibration reduction measures were proposed.The main work and conclusions are as follows:(1)Based on the current situation of railway development in our country,the research background and the significance of this work were introduced,and the research situation of vehicle-track-bridge coupled vibration theory and its application status in bridge-sound barrier dynamic response system were systematically summarized from the perspectives in the time domain and frequency domain.(2)Field tests of vehicle-induced vibration of a bridge-sound barrier system were carried out on a railway viaduct,the distribution law of vibration was analyzed in the time domain and frequency domain,and the results showed that the vibration acceleration of the rail,box girder roof and the middle of the sound barrier column showed obvious periodic changes in the time domain.The vibration energy was selectively amplified or attenuated during the transmission process,the main frequency range was gradually reduced,and the total vibration level of the sound barrier was higher than that of the box girder vibration.(3)A 1/4 vehicle-ballasted track vertically coupled system model was established in the frequency domain.The dynamic flexibility method was used to solve the dynamic wheel-rail force,and it was iuputted as an excitation into the finite element model of the bridge-sound barrier system to analyze the resonance response.So the vehicle-induced vibration response results of the structural system were obtained,and finally the reliability of the model was verified by the field measured datas.(4)Based on the vehicle-induced vibration analysis model of the bridge-sound barrier system,the distribution law of vehicle-induced vibration of the bridge-sound barrier system was analyzed,and the influence of parameters such as vehicle speed,driving direction,bridge span and column size was discussed,and further proposed Vibration reduction measures showed that the vibration of the box girder and column both showed a trend of increasing from the end to the middle of the span,and both increased with the increase of vehicle speed.For every 30km/h increased in vehicle speed,the total vibration level of the box girder roof increased by about 2d B.When the vehicle speed reached 200km/h,the vibration of the sound barrier column was significantly intensified,and the driving direction had no obvious influence on the vibration of the box girder.Driving near the sound barrier would increase the vibration of the sound barrier column by about 2d B.The vibration of the box girder and the column increased as the span increases.But the impact of span was limited.When the span was increased by 16 m,the total vibration level increased only by 2～3d B.The vibration of the sound barrier column decreased with the increase of the plate thickness.The thickness of the box girder plate,the cross-sectional form,the addition of flange braces and other measures could effectively reduce the vehicle-induced vibration response of the bridge-sound barrier structure system. |
PDF Full Text Request