列车作用下青藏铁路路基动力响应试验

目的分析研究多年冻土区青藏铁路在列车动荷载作用下路基的稳定性及振动衰减规律．方法选取青藏铁路北麓河段三个典型试验断面，在春季进行了列车荷载作用下的路基动力响应现场试验，采集路基、边坡、道床3处振动数据，统计计算了青藏铁路客车与货车行驶时路基振动的最大和平均加速度幅值，对实测数据进行了功率谱分析．结果路基上货运和客运列车的竖向最大加速度分别为2．2132m／ss^2和2．0004m／ss^2，对应的平均加速度分别为0．1495m／s^2和0．1143m／ss^2，道床上的振动明显减小．在T28次客运列车的作用下，对于断面Ⅲ，C3测点在振动频率为25Hz、38Hz、46Hz，55Hz出现峰值，能量集中在18～53Hz．边坡C4测点振动能量集中在20—65Hz，C5测点的优势频段为20—80Hz．结论路基上货运列车的振动比客运列车振动大，同一断面竖向衰减速度大于横向，素土路基各方向衰减小于块石路基，下一测点加速度峰值大致减小为相邻上一测点的1／10．

Test Study on Dynamic Response of Qinghai-Tibet Railway Subgrade under Trains

The stability and vibration attenuation law of Qinghai-Tibet railway in permafrost regions under dynamic trains load were studied. The subgrade dynamic response field test study were carried out in spring at three typical test section in Beiluhe, the vibration data were collected at subgrade, slope and track bed. The maximum and average subgrade vibration acceleration amplitude under passenger and freight trains were sta- tistical, the power spectrum were analyzed for collected data. The vertical maximum acceleration on the sub- grade were 2. 213 2m/ss^2 and 2. 000 4 m/ss^2 respectively for freight and passenger trains, the average acceleration was 0. 149 5 m/ss^2 and 0. 114 3 m/ss^2 respectively ,vibration at track bed were significantly reduced. Under T28 passenger train, at section Ⅲ, there were frequency peak in 25 Hz ,38 Hz ,46 Hz and 55 Hz, vibrated energy is concentrated in 18 - 53 Hz in C3 measuring point,20 -65 Hz in C4 measuring point and 20-80 Hz in C5 measuring point. The freight train vibration were higher than those of the passenger train, the vertical attenuation rate was faster than that of transverse in the same section. Attenuation rate of plain soil subgrade was slowed than that of stone subgrade in all directions, the acceleration peak was roughly 1/10 that of the upper adjacent measuring point.