Research On Vibration And Noise Control Effect Of Steel Spring Floating Slab Track In Urban Rail Transit Viaduct

With the large-scale development of urban rail transit in China,the vibration and noise problems of urban rail transit viaducts are becoming the focus of society and industry.The steel spring floating slab track can reduce the vibration energy transmitted to the bridge structure,thereby effectively controlling the vibration and noise radiation of the viaducts.Based on the engineering background of the Jiahua Bridge of Chongqing Rail Transit Line 9,this thesis studies the vibro-noise reduction characteristics of the steel spring floating slab track on the rail transit viaduct.The specific research contents and main conclusions are as follows:(1)The research background and significance of this thesis are briefly described from three aspects which are the developments of urban rail transit,the harm of viaduct noise and the applications of steel spring floating slab track.Current research status concering the modeling method,vibration and noise reduction performance and dynamic characteristics of steel spring floating slab track and so on are summarized,and the basic theory of numerical simulation of structural vibration and sound radiation is introduced.(2)Based on the receptance method,the train-track coupled vibration in frequency domain analytical model is used to obtain the force transmitted to the bridge,combined with the hybrid FEA-BEM method,the vibration and noise prediction of the track-brigde system is carried out,and the field test of viaducts in Guangzhou Metro Line 4 is adopted to verify the model.(3)According to the established vibration-noise prediction model of the track-bridge system,the vibration and noise reduction effect of the steel spring floating slab track on Jiahua bridge and the noise distribution law of Jiahua bridge are studied.The results show that: compared with the ordinary embedded track,the steel spring floating slab track can reduce the overall vibration acceleration level of the bridge by 25.2 dB,and the overall sound pressure level of each field point is reduced by 16.6 dB;the noise attenuation of the bridge structure is slow,the average attenuation of the sound pressure level in the range of 0 to 100 m from the centerline of the bridge under two different track structures is about 0.20 dB/m.(4)The structure-borne noise prediction model of steel spring floating slab is established.The vibration characteristics and structure-borne noise radiation characteristics of the floating slab are analyzed,and the influence of floating slab structure-borne noise on its noise reduction effect is discussed.The parametric studies of floating slab noise are carried out.The results show that: considering the noise of the floating slab,the noise reduction effect of the steel spring floating slab track is reduced by 12.8 dB on average,the overall sound pressure level of some field points is even increased;affected by the shielding effect of the bridge and the reflection of the acoustic wave on the bridge,the noise of the floating slab has less influence on the noise under the bridge;the A-weight overall sound pressure level of the floating slab can be reduced by approximately 12 dBA by replacing normal rail fastener(60 MN/m)by the high-elastic fastener(6 MN/m).The research results can provide reference for the application of steel spring floating slab track on the vibration mitigation and noise reduction project of viaduct.