下沉式地铁车辆段咽喉区车致振动特性

采用触发采集方式现场实测了某下沉式地铁车辆段咽喉区钢轨、道床、地面、楼板及盖板的振动加速度, 采用插入损失、1/3倍频谱、Z振级曲线拟合等方法分析了现场实测数据, 进而分析了下沉式地铁车辆段咽喉区的振源特性与地铁振动沿盖板和不同层楼板的传播规律。分析结果表明: 在频域上, 钢轨比道床振动频带更宽, 没有明显的主频段, 其振动分布在800 Hz以内, 道床则有明显的主频段, 主要分布在80~200 Hz; 下沉式地铁车辆段地下1、2层钢轨至道床振动衰减幅度分别约为29.9、10.4 dB; 列车引起盖板的振动响应随测点与行车轨道中心线距离的增大呈线性衰减规律, 其线性衰减率约为0.2 dB·m-1; 由于边墙对振动的反射与折射, 振动传至盖板端部时出现局部放大现象; 列车无论在地铁车辆段端部还是在中间股道行车, 随着测点与行车轨道中心线距离的增大, 车辆段盖板振级在2.5、5.0 Hz低频处基本不变, 在10 Hz处衰减缓慢, 在25、40、80 Hz中高频处衰减明显; 列车在地下1、2层行车时诱发的振动的向上传播呈逐层衰减规律, 列车在地下1层行车引起的盖板振动比其在地下2层行车时大约16.1 dB; 下沉式地铁车辆段咽喉区轨道接头多、道岔多的特点导致该区域盖板车致振动响应突出, 需重点对该区域进行减振设计。 

Train-induced vibration characteristics in throat area of sinking metro depot

The vibration accelerations of rail, ballast bed, ground, floor and cover plate in the throat area of a sinking metro depot were measured on site by the trigger acquisition method. The field measured data were analyzed by the methods of insertion loss, one-third octave band spectrum and curve fitting of Z direction vibration level. Furthermore, the vibration source characteristics in the throat area of sinking metro depot and the transmission law of vibration along the cover plate and different floors were analyzed. Analysis result shows that in the frequency domain, the frequency band of rail vibration is wider than that of ballast bed, and there is no obvious main frequency band. The vibration distribution of rail is within 800 Hz. While the ballast bed has an obvious main frequency band within 80-200 Hz. The vibration attenuations from the rail to the ballast bed at the first and second floors underground are about 29.9 and 10.4 dB, respectively. The train-induced vibration response of cover plate decreases linearly with the increase of distance between the measuring point and the center line of running track, and the linear attenuation rate is about 0.2 dB·m-1. Due to the reflection and refraction of the side wall to the vibration, the local amplification phenomenon occurs when the vibration is transmitted to the end of cover plate. No matter the train is running at the end of metro depot or in the middle track, with the increase of distance between the measuring point and the center line of running track, the vibration level of cover plate is basically the same at the low frequencies of 2.5 and 5.0 Hz, decreases slowly at 10 Hz, and decreases obviously at the middle and high frequencies of 25, 40 and 80 Hz. The upward propagation of train-induced vibration shows a floor-by-floor attenuation law. The vibration of cover plate caused by the train operation at the first floor underground is about 16.1 dB greater than that at the second floor underground. The characteristics of many rail joints and turnouts in the throat area of sinking metro depot lead to the prominent vibration response of cover plate in this area. It is necessary to focus on the vibration reduction design of this area.