桥上列车高速运行引起的地面振动试验研究

Field Test of Ground Vibration Induced by High-Speed Train on Elevated Bridge

为了研究高速铁路高架段车致地面振动的传播和衰减规律，以津秦客专线32m简支梁桥区段为工程背景，实测高速列车以速度250～385km／h通过时的三向地面振动响应，并对实测数据进行时域和频域分析．研究结果表明：近场测点的加速度时程呈现出明显的列车周期性加载现象，轴距及前后车相邻转向架间距的激励频率起主要作用；地面各测点在顺桥向、横桥向和垂向3个方向上的振动优势频率范围为25～80Hz；随着距离的增加，垂向地面振动在优势频段显著衰减，而顺桥向和横桥向地面振动在1—80Hz频段内均明显衰减；各测点在各测试车速下，垂向地面振动比顺桥向和横桥向大，而同一测点在顺桥向和横桥向的地面振动加速度级最多相差2dB；顺桥向和横桥向地面振动在距振源约30m处出现放大现象；车速为250～320km／h时，近场总体振动加速度级随车速增加而增大约6dB，但车速为330—385km／h时的各测点总体振动加速度级相差不超过2dB．

To study the ground vibration induced by high-speed trains across bridges, a field test was carried out in vicinity of a simply supported box-girder with a span of 32 m on Tianjin-Qinhuangdao railway line. Ground vibrations in the longitudinal, lateral and vertical directions were measured with train speeds in the range 250 -385 km/h. The test data were analyzed in both time and frequency domains. The results show that cyclical peaks of acceleration can be clearly distinguished in the near field, and the excitation frequencies of wheelbase and the adjacent bogie space of the front and rear cars make the main contributions. The dominant frequency of ground vibration in the three directions is 25- 80 Hz, and the vertical ground vibration attenuates mainly in the dominant frequency band; however, the longitudinal and lateral ground vibrations obviously attenuate in 1 -80 Hz. For all test train speeds and all test points, the vertical ground vibrations are stronger than the longitudinal and lateral ground vibrations, and the maximum difference of vibration acceleration levels （VALs） between the longitudinal and lateral ground vibrations is about 2 dB. A phenomenon of amplification for the longitudinal and lateral ground vibrations is observed at the distance of about 30 m. Overall VAL of the near field increases about 6 dB when the train speeds increases from 250 to 320 km/h. However, thedifferences of overall VALs at all locations are less than 2 dB while speeds in the range of 330 - 385 km/h.