Analysis Of Vibration And Noise Characteristics Of Light Rail Vehicles-Ballasted Track-Viaduct

The environmental vibration and noise problem induced by urban rail transit has been widely concerned.Compared with underground railways,the railways on viaducts have the advantages of low cost and high construction safety,and are widely used in urban rail transit.However,viaducts are directly exposed to the air,and the effects of vibration and radiated noise are more prominent.Light rail as an important part of the rail transit system.In China,the development period is short,and people have limited awareness of the vibration and noise problems induced by light rail.When light rail vehicles running on viaducts,the vibration and noise problems caused by it will inevitably become the focus of attention.Based on the investigation and analysis of vehicle,track and bridge dynamics research,this paper establishes a light rail vehicle-ballasted track-viaduct coupled vibration analysis model and a bridge radiated noise analysis model.The vibration response of the system and the radiated noise characteristics of the bridge when the light rail vehicle is running are analyzed.And analyze the influence of each parameter on the vibration and noise of the bridge from the three aspects of vehicle,track and bridge,it can provide theoretical support for the vibration and noise reduction of light rail vehicles-tracks-viaducts.(1)Establish a vehicle-track-bridge coupled vibration analysis model and a bridge radiated noise analysis model.Based on the method of combining multi-body dynamics and finite element,a three-dimensional coupled vibration analysis model of light rail vehicle-ballasted track-viaduct was established;the method of combining acoustic finite element and infinite element was used to establish a bridge radiation noise analysis model,and Compared with the literature results,the reliability of the calculation method and model adopted in this paper is verified.(2)Analysis the coupling vibration of light rail vehicle-ballasted track-viaduct system.In this paper,the dynamic simulation and analysis platform FORSYS with independent intellectual property rights is used to solve the vibration response of the six-axis articulated light rail vehicle-ballasted track-viaduct.The safety and stability of the vehicle,the dynamic characteristics of the track structure and the dynamic characteristics of the bridge structure are analyzed,the results show that the light rail vehicle is safe and stable,and the dynamic performance indexes of the track and bridge structure meet the specification requirements.(3)The time domain and frequency domain characteristic analysis and spatial distribution characteristic analysis of bridge radiated noise are analyzed.Based on the bridge vibration response in the time and frequency domains,the method of combining acoustic finite element and infinite element is used to predict the bridge radiated noise in the time and frequency domains,and the two results are compared to verify the accuracy of the two methods.The spatial distribution characteristics of bridge radiated noise are analyzed by the method of frequency domain solution.It is found that the radiated noise of the bridge is mainly distributed left and right centered on the flange and web,and up and down centered on the bottom plate,on the same section,as the distance increases,the sound pressure level decreases continuously,and the attenuation speed decreases continuously.(4)The influence of the dynamic parameters of the light rail vehicle-track-bridge system is analyzed.Based on the established vibration model and noise model,the influence of three parameters of vehicle,track and bridge on vibration and noise is analyzed.In the influence of vehicle parameters,the change of load has little influence on the vibration and noise of the bridge,while the influence of the running speed is more obvious,and the vibration and noise of the bridge increases with the increase of the vehicle speed.In the influence of track parameters,the use of low-rigidity fasteners or ballasted track can effectively reduce the vibration and noise of the bridge.In the influence of bridge parameters,compared with the U-shaped bridge,the radiated noise of the box-shaped bridge structure is smaller,but it has no shielding effect on the rail noise,and the U-shaped bridge has a better noise reduction effect when the rail noise is large.Reducing the thickness of the U-shaped bridge bottom plate will rapidly increase the radiated noise of the bridge,so it is not suitable to use a U-shaped bridge structure with a smaller bottom plate thickness.