列车荷载激励下夯土遗址的振动响应特性研究

Study on the Vibration Response Characteristics of Rammed Earth Sites under Train Load Excitation

摘要:

铁路列车运行引起的场地振动为铁路周边建筑遗址带来不可忽视的影响，为研究列车荷载激励下夯土遗址不同高度处的振动响应以及列车类型、速度、编组等因素对其的作用规律，以夏官营古城城墙为研究对象，基于多种工况开展现场原位监测与地质调查，从时域、频域等多方面分析城墙旁列车运行引起的振动响应并对比现有标准，确定振动强度及对城墙的影响。研究结果表明：列车行驶引起的城墙振动速度峰值和有效值随墙高增大呈波动性衰减，货车引起的城墙振动速度响应大于客车，在城墙中部区域均出现了振动速度放大的现象并且达到振动最大值；城墙振动速度与车速、编组及载重成正比，各测点振动优势频率范围为40~70 Hz，城墙中部区域频率放大效应明显，振动放大区域受到列车车速和编组长度影响；城墙Z振级衰减特性与速度响应变化规律相同，货车Z振级最大值为80.29 dB，客车为76.65 dB，相比40 Hz以上的振动频率，10~40 Hz的振动频率衰减慢，对墙体造成的损伤更大。结合已有振动标准及土遗址基本性质，列车运行将对夏官营古城城墙产生影响，研究结果可为相关土遗址的保护措施提供参考。

Abstract:

The ground vibrations induced by railway train operations significantly impact architectural sites adjacent to railways. To investigate the vibration response at different heights of rammed earth sites under train load excitation and the influence of factors such as train type, speed, and formation, this study focused on the walls of Xiaguanying Ancient City as a case study. In-situ monitoring and geological surveys were conducted under multiple operational conditions. The vibration responses caused by train operation next to the city wall were analyzed from time domain, frequency domain, and other aspects, compared with existing standards to determine the vibration intensity and its impact on the city wall. The results showed that the peak and effective values of vibration velocity caused by the train decreased in a fluctuating manner as the wall height increased. The vibration response caused by freight trains was greater than that caused by passenger trains. Vibration velocity amplification was observed in the central region of the wall, where the maximum vibration values were reached. The vibration velocity of the wall was proportional to train speed, formation, and load. The dominant vibration frequency at all measurement points ranged from 40 to 70 Hz. The frequency amplification effect was significant in the central region of the wall, and the vibration amplification area was influenced by train speed and formation length. The Z-vibration level attenuation characteristics of the wall followed the same pattern as the speed response, with the maximum Z-vibration level being 80.29 dB for freight trains and 76.65 dB for passenger trains. Compared to vibration frequencies above 40 Hz, vibration frequencies between 10 and 40 Hz attenuated more slowly, causing more damage to the wall. Based on existing vibration standards and the basic properties of earth sites, train operation impacts the walls of Xiaguanying Ancient City. The research results provide valuable insights into protective measures for similar earthen heritage sites.