Research On Noise Reduction Measures Of High Speed Railway Box Girder Bridge Based On Stiffened Plate Design

As the main artery of rail transportation,high-speed railway has been vigorously developed in our country.The rapid development of high-speed railway has greatly shortened people’s travel time and narrowed the space and time distance of major cities.In our country,the proportion of high-speed railway line bridge is very large.When the train passes through elevated bridge section,the vibration energy is transferred from track structure to bridge structure,causing the vibration of bridge and then radiating the low frequency noise outward.With the continuous improvement of train speed and the large-scale construction of high-speed railway comprehensive network,the distance between high-speed railway and residential areas is narrowed.Therefore,the low-frequency structural noise of high-speed railway bridge will have a great impact on the residential areas along the line and the sound environment inside the car.Therefore,the research on noise reduction measures of viaducts is of great significance.In this thesis,32 m simply-supported box girder bridges of high-speed railway are taken as the research object.Dynamic models of different rail-box girder bridges and acoustic boundary element models of box girder bridges are established by using train-track-bridge interaction theory and acoustic boundary element method,and vibration and acoustic radiation characteristics of box girder Bridges are systematically analyzed.According to the acoustic and vibration characteristics of the box girder bridge,the research on the noise reduction measures of the box girder bridge is carried out.The main method is the reinforcement design of the box girder bridge.The vibration and noise reduction effects of different reinforcement methods are studied systematically,and the noise reduction mechanism of the reinforcement design is further analyzed by the vibration characteristics of the box girder bridge and the structural acoustic theory.On this basis,the noise reduction effect of reinforcement design of box girder bridge with different track structure is analyzed,and the influence of different track structure on the sound radiation of box girder bridge is further studied.The results show that the vibration of high-speed railway box girder bridge under external excitation is mainly manifested as the overall vibration of the box girder bridge and the local vibration of the roof,among which the local vibration of the roof is the most important vibration characteristic.The acoustic radiation of box girder bridge is mainly distributed in the sound field on the bridge,and the maximum acoustic power is 106.46 d B.According to the sound radiation contribution of the panels of the box girder bridge,the top plate is the most important sound radiation contribution panel of the box girder bridge,so the subsequent noise reduction design mainly takes the top plate as the control object and carries on the reinforcement design.The transverse reinforcement,longitudinal reinforcement and longitudinal and transverse reinforcement at the same time have good vibration reduction effect.Compared with the other two reinforcement methods,the transverse reinforcement has less noise reduction effect,and the longitudinal and transverse reinforcement at the same time has the best vibration and noise reduction effect.Longitudinal,longitudinal and transverse reinforcement at the same time has a great influence on the natural vibration characteristics of box girder bridge in low frequency band.Therefore,the phenomenon of acoustic radiation amplification caused by resonance of box girder bridge can be avoided to a certain extent in low frequency band,and the acoustic radiation efficiency of box girder bridge in low frequency band can be effectively inhibited,thus reducing the overall acoustic radiation capacity of box girder bridge.Compared with laying CRTS-Ⅰ type plate-type ballastless track,laying CRTS-Ⅲ type plate-type ballastless track has better noise reduction effect in the reinforced design of box girder bridge roof,and CRTS-Ⅲ type plate-type ballastless track has better vibration and noise reduction performance.