高速铁路路堑段地面振动试验研究及数值分析

为研究高速铁路路堑在高速列车荷载下的地面垂向振动随距离传播规律,对宝兰高铁路堑段地面垂向振动进行现场试验,对现场试验的数据从时域和频域两个方面进行分析揭示地面垂向振动加速度响应特征。结果表明,路堑垂向振动加速度在距离线路中心线12.5～40 m总体呈衰减趋势,靠近线路中心线处12.5～20 m处垂向振动加速度衰减较快,较远处20～40 m处衰减速度较慢。地面垂向振动加速度在各测点处由60 Hz及100 Hz附近的频率成分主导,随着距离的增大,110 Hz左右的高频成分衰减很快,到了距线路中心线20～40 m,振动加速度在60 Hz左右的频率成分占优。依据现场工况,建立了列车-轨道-路堑-地基数值分析模型,并通过数值试验的方法,设置不同的场地速度特性,分析不同场地条件对路堑振动响应的影响。数值分析表明,场地速度特性(覆盖层与下卧层模量比、覆盖层厚度)是影响地面振动剧烈程度的重要因素,地基覆盖层与下卧层模量比越大,地面振动越强烈,模量比一定,覆盖层厚度越小,地面振动越大。

Experimental Study and Numerical Analysis of Ground Vibration in Cutting Section of High-speed Railway

In order to study the vertical vibration propagation law of high-speed railway cutting with distance under high-speed train load, a field test is carried out on the ground vertical vibration of the cut section on Bao-Lan high speed railway. The response characteristics of the ground vertical acceleration are revealed by analyzing the data of field test in terms of time domain and frequency domain. The results show that the vertical vibration acceleration of the cutting tends to attenuate between 12.5 m and 40 m from the central line of the track. The attenuation rate of the vibration acceleration near the central line of the track is faster than that at the point of 12.5 m or 20 m near the central line of the track, and the attenuation rate is slower than that at the point of 20～40 m in the distance. The ground vibration acceleration is dominated by the frequency components near 60 Hz and 100 Hz at each measuring point. With the increase of the distance, the high frequency component of 110 Hz attenuates rapidly, and the frequency component of the vibration acceleration around 60 Hz dominates between 20 and 40 m of the central line of the track. According to the field working conditions, a numerical analysis model of train, track, cutting and foundation is established, different site velocity structures are set up by means of numerical test, and the influences of different site conditions on the vibration response of the cutting are analyzed. The numerical analysis shows that the velocity structure of the ground(the ratio of the modulus of the overburden to the underlying layer, the thickness of the overburden) is an important factor affecting the intensity of the ground vibration. The greater the modulus ratio of the ground cover to the underlying layer, the stronger the ground vibration and the constant modulus ratio. The smaller the overlay thickness, the greater the ground vibration.