Study On Structure Noise Radiation Characteristics Of Viaduct Bridge Under Slab Track Of High Speed Railway

The scale and the mileage of high speed railway of our country are in a leading positionin the world and in the future China high-speed railway will be large-scale constructed andput into operation. Due to the riding comfort, good stability and less repair requirements ofhigh speed railway, the high speed railway has a characteristic that the proportion of bridge isvery large. And the bridge is also a key technology of high speed railway. With theimprovement of train speed, the dynamic interaction of vehicle-track-bridge system isintensified, which leads to more serious structure vibration and noise radiation.In this paper, the32m concrete simply supported single-box elevated bridge used in highspeed railway is taken as the research object and the type of slabs of track system is CRTS-I.Based on the vehicle-track-bridge coupling dynamic theory and the acoustic theory, thewheel/rail vertical force excited by German railway spectra of low irregularity is taken as theload boundary conditions to analyze the vibration responses of the elevated box bridge whichis then taken as the acoustic boundary conditions to investigate its structure noise radiation,the peak value of the noise and the influence of some parameters on the structure noiseradiation. Finally, the influence of the position of steady-state load on the box bridge structurenoise is studied by modal acoustic transfer vector method, and the further research of thepanel contribution of each plate of the elevated bridge to the sound pressure is carried out.The results show that:(1) Compared with the bottom plate and the web plates, the top plate has the intensestvibration in terms of the elevated box bridge used in CRTS-I slab ballastless track section, butthe mode of them are almost the same, and they are mainly concentrated in the lowfrequency range of0-200Hz, and the peak are mostly in the frequency range of10-100Hz;(2) The shell element model can better show the self vibration characteristics of boxbridge, superior to the traditional beam element model; under the bridge and in the far soundfield, the sound pressure level of field point increases with the increase of the distance of fieldpoint to ground; in the transverse of bridge, the sound pressure level of field point decreaseswith the increase of the distance of field point to bridge and the lower frequency, the moreobvious the decreasing trend is; when the center frequency was16,25,80,100Hz, the soundpressure of each point has the more value; in80-100Hz, the sound pressures around the bridgeare larger than that of other sites;(3) The factors which have influence on the bridge structure noise radiation mainlyincluding the bridge structure vibration, the sound radiation efficiency and vibration-acousticcoupling; (4) The ground reflection and the velocity of train have obvious effect on the bridgestructure noise radiation, and the influence of stiffness of fasteners on that is weak, and thesound barriers almost have on influence on it.(5) Modal acoustic transfer vector can adequately combined vibration characteristics ofthe box itself, so it can more accurately reflects the influence of the box bridge itself structurecharacteristics on its structure noise radiation; under different frequencies, the contribution ofa plate to field points is different, and it can be divided into positive, negative and neutralcontribution.