成灌铁路CRTS Ⅲ型板式无砟轨道路基段环境振动特性

Environmental vibration characteristics of CRTS Ⅲ slab ballastless track on the embankment of Cheng-Guan fast railway

为研究CRTSⅢ型板式无砟轨道环境振动特点,对成灌快铁某路基段地面振动进行了现场测试,分析了不同测点地面振动加速度时程特点、频谱特征和铅垂向振级随距离的衰减特性。结果表明：CRH 1型动车组以181 km/h速度通过测试路基地段时,地面振动持续时间约6 s,距线路中心线22 m处振动峰值加速度为60 mm/s2,由于传播过程中的几何阻尼和材料阻尼作用,52 m处振动峰值加速度衰减为10 mm/s2;在22 m处振动能量主要分布在20~60 Hz,传播过程中高频振动随距离衰减更快,52 m处振动能量主要分布在20~23Hz;地面振动垂向振级随距离的衰减符合对数规律。

The present paper takes it as the research object to study the environmental vibration characteristics of CRTS Ⅲ slab ballastless track of Cheng-Guan fast railway construction. As is known,the CRTS Ⅲ slab ballastless track is a modified track type,which makes it of extreme importance to carry out the intensive ground vibration tests via the INV3062 T data acquisition system and 941 B acceleration sensors, whereas the testing sites should be chosen at a two-layer ground,consisting of a layer of silt clay 1 to 2 meters thick on the thick-bedded pebble soil over30 meters,with the four measurement points evenly scattering at22 meters,32 meters,42 meters and 52 meters from the railway center,respectively,in a straight line and perpendicular to the railway line. At the same time,we have tested and recorded the ground vibrations when the CRH 1 EMU passed through the testing site and analyzed the historic situation of the ground vibration via the acceleration time and the acceleration frequency spectrum.The results of our measurements show that the ground vibration duration has to last about 6 seconds when CRH 1 EMU pass through at a speed of 181 km / h. Whereas the peak acceleration of the ground vibration at 22 meters from the central line turns to be 60 mm / s2,with a gradual attenuation to 20 mm/s2,14 mm/s2 and 10 mm / s2 at the 32 meters,42 meters and 52 meters,respectively,for the radiation and material damping. Furthermore,in the process of wave propagation,the frequency vibrations tend to attenuate at a lower rate than at the higher rate. Moreover,the vibration frequency spectra measured on the ground tend to be distributed in a range from 20 Hz to 60 Hz at 22 meters from the line centre and 20 Hz to 45 Hz at 32 meters. But,in the distance away from 42 meters and 52 meters,the dominant frequency range should be between 20 Hz and 23 Hz. On the other hand,it is also necessary to work out the vertical vibration rate via the two frequency weighing curves of Z and Wk. And,finally,it is possible to find both the Z vibration level and Wkvertical vibration level of the ground vibration attenuated with increase of the distance from the measuring points to the line centre,in accordance with the logarithmic law.