Research On Vibration And Structural-borne Noise Prediction And Evaluation In High-speed Railway Bridges Under Extreme Cold Conditions

With the Moscow-Kazan high-speed railway in Russia as the engineering background,research was conducted on the vibration and noise in viaduct section.Compared with the domestic high-speed railway,the Moscow-Kazan high-speed railway has two major new technical problems: ultra-low temperature and ultra-high speed.Existing domestic research cannot be used as a reference,so it is necessary to predict the bridge vibration and noise under the two major conditions in order to be guide the vibration and noise reduction design of the viaduct section.On the other hand,for the evaluation of low-frequency noise radiated from bridge structures,the A-weighted sound pressure level is usually adopted,which deviates from people’s feelings.Therefore,it is necessary to introduce new indicators for evaluation.In this paper,a psychoacoustic evaluation index is studied.Using the field test data of an elevated section of an intercity railway,the psychoacoustic evaluation index for the evaluation of environmental noise in viaduct section is compared with A-weighted sound pressure level.The results show that the environmental noise dominated by low-frequency components is most representative of sharpness,while the environmental noise dominated by high-frequency components is most representative of total loudness.A model based on the rigid-flexible coupling theory is built to carry out prediction research on the ultra-low temperature problem,considering three parameters that are greatly affected by temperature: fastener stiffness,bridge support stiffness and air density.The literature survey and summary concluded that the important facts at-50℃,-30℃,-10℃ and+ 20℃ were designed,and then the model was used to predict the vibration response and secondary noise radiation from track structures and bridges.The results show that: 1)As the temperature decreases from 20℃ to-50℃,the vertical acceleration of the rail and track slab has been increasing,and when the temperature decreases from-30℃ to-50℃,the increase rate is the largest,while the vertical acceleration of the bridge first increases,latter decreases and then increases again,and the maximum value appears at-10℃;2)As the temperature decreases,the vibration acceleration levels of the rail,track slab and bridge are respectively 63Hz ～ 200Hz,20Hz ～ 200Hz and 40Hz ～ 200Hz increase significantly;3)As the temperature decreases from 20℃ to-50℃,the linear total sound pressure level of the secondary noise of the bridge structure increases,and the change law was consistent with the vertical acceleration of the bridge.Compared with the temperature at 20℃,the sound pressure level at 20Hz and within 40Hz ～ 80Hz is obviously increased at-50℃.Finally,this paper analyzes the vibration response and noise radiation of various bridge components at a running speed of 400km/h,and compares it with the three existing domestic high-speed rail speed grades.The results show that: 1)When the train is running at 400km/h,the dynamic response of each component of the bridge meets the limit requirements in the specification;2)When the speed increases from 250km/h to 400km/h,the vibration increases,and the biggest increase is from 350km/h to 400km/h.In the future;3)When the train speed is increased from 250km/h to 400km/h,the vibration of rails and track slabs increases mostly at 80Hz,and the vibration of bridge increases mostly at 63Hz;4)As the train speed increases to 400km/h,the linear total sound pressure level of bridge born noise increases extremely,especially at 63Hz.