| The rapid development of high-speed railway in China has made an indelible contribution to the rapid growth of the national economy.While high-speed railway helps national economic development and facilitates passenger travel,the noise caused by high-speed trains has attracted more and more attention and become an urgent problem to be solved.When the high-speed train is running on the elevated line,the bridge structure is excited to produce vibration,and then the secondary structural noise radiating outward is formed.Noise not only affects the normal work,life and rest of the residents along the line,but also lasts for a long time,and it will cause deep damage to the body over time.Therefore,it is of great significance to study the acoustic radiation prediction and sound-vibration characteristics of high-speed railway viaduct structures.The study of bridge structural noise involves many objects and fields,and the most commonly used numerical calculation methods are boundary element method and statistical energy method.Most of the high-speed railway viaducts in China are reinforced concrete structures,and their vibration radiation noise is low frequency,so the boundary element method is often used to study the structural acoustic radiation,but the boundary element method needs to use numerical method to deal with the singularity problem in calculation.as a result,the solution speed is slow and the efficiency is low.Therefore,in this paper,the wave superposition numerical calculation method is applied to the study of acoustic radiation of high-speed railway viaduct,mainly from the following aspects: First of all,taking the high-speed railway viaduct box girder bridge as the research object,based on the vehicle-track-bridge dynamics theory,the vibration response of the box girder bridge is obtained by the finite element method,and the vibration response of each plate of the box girder bridge is compared in time and frequency domain.the main vibrating plates are analyzed.Through the CRH2 dynamic model,and the wheel-rail force is applied to the track-bridge finite element model by moving load,the vibration response of the bridge is obtained.Then,based on the wave superposition theory,the correctness of the program is verified by three examples: pulsating sphere source,cube box and simply supported plate.Secondly,combined with the boundary element method,the prediction model of structural noise of box girder bridge is established,and the dynamic response of the bridge is the acoustic boundary condition,and the structural radiation noise of box-girder bridge is obtained.Systematic analysis is carried out from three aspects: sound field distribution,sound radiation law and sound radiation contribution of each plate.Finally,the acoustic radiation from the roof of the box girder bridge and the integral box girder bridge is solved by using the wave superposition method,and its feasibility is verified by exploring the application of the wave superposition method to the noise field of the bridge structure.The influence on the results is analyzed from two aspects of the equivalent source position and the surface vibration velocity of the structure.Through the study of this paper,the following conclusions are drawn.Firstly,the vibration of the box girder bridge is mainly manifested as the overall vertical bending vibration and local vibration.,in which the local vibration of the roof is the most intense.When the high-speed train passes through the viaduct box girder bridge,the vibration acceleration amplitudes of the roof,operating side web,unrunning side web and bottom plate in time and frequency domain decrease in turn,that is,the vibration of the roof is the most intense.The vibration of the plate of the box girder bridge is mainly low-frequency vibration.Due to the resonance,the amplitude of the vibration of the bottom plate and the unrunning web is larger when it is lower than 20 Hz.Secondly,when the high-speed railway double-track box girder bridge is running on one side,the radiated sound field is not symmetrically distributed in the up and down,left and right directions,and is more dense in the area above the roof and below the bottom plate.Because the train runs on a single line,the left and right directions also show asymmetric distribution;when the frequency is low,the sound field distribution is relatively regular,and the sound field distribution is chaotic with the increase of frequency.When the train passes through the bridge,the radiated noise of the box girder bridge decreases gradually with the increase of the distance;the frequency of the radiated noise of the reinforced concrete box girder bridge is mainly in the 0～250Hz frequency range;the noise value of box girder bridge radiation below 50 Hz exceeds the prescribed limit,which should be paid more attention to.When the train is running to induce the box bridge to radiate noise,each plate radiates the noise as a sound source,and the sound pressure value of the sound field point is the result of the joint action of the sound pressure of each plate,in which the roof contributes most to the sound radiation pressure,which is the main radiation sound source.Thirdly,the position of the equivalent source and the surface vibration velocity of the structure are two important factors that affect the prediction accuracy of the wave superposition method.For the simple structure,the equivalent source location has little influence on the prediction results;for the box girder bridge structure,the equivalent source location will directly affect the prediction accuracy,and even make the results distorted.The complexity of the surface vibration velocity of the structure will directly affect the accuracy of the prediction results.The high-speed railway viaduct is a reinforced concrete structure,and its radiated noise is low-frequency noise,so it is accurate to use the wave superposition method to predict the structural noise in the low-frequency band.Therefore,it is feasible to apply the wave superposition method to the structural noise prediction of high-speed railway viaduct. |
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