重载铁路过渡段路基动力响应特性试验研究#br#

掌握列车移动荷载作用下路基的动力响应特性可为路基沉降预测，状态评估提供依据。开展重载铁路过渡段路基动力响应测试，研究动位移峰值沿线路纵向及边坡方向的变化规律，分析路肩处动位移峰值的随机分布规律。研究列车动荷载作用下路基的动力响应特征，并揭示振动能量沿路基边坡的衰减规律。结果表明：列车动荷载对路基的作用具有明显的周期性，可将相邻车厢的两个前后转向架作为一个加载单元，在该加载单元的重复作用下路肩处的动位移峰值服从正态分布。重载列车动荷载作用下路基的振动频率主要分布在0~20Hz范围内，振动能量从路肩向坡脚方向衰减剧烈，基床层受列车动荷载影响显著，而基床以下路基受列车动荷载影响非常微小。分析结果有助于评估列车荷载作用下路基的瞬时及长期动力稳定性，同时为采用模型试验及数值分析手段研究路基动力响应特性时准确模拟重复列车动荷载提供了思路。

Experimental research on dynamic response characteristics of transition subgrade induced by heavy-haul trains

The dynamic responses of subgrade under moving train loads can provide reference for subgrade settlement prediction, condition evaluation and so forth. The field dynamic tests were conducted on transition subgrade in Shuo-Huang heavy-haul railway in China. The variation rules of peak dynamic displacements along the track and the subgrade slope were analyzed, and the random distribution characteristics of the peak dynamic displacements at subgrade shoulder were studied. The response characteristics of subgrade during the train passage were investigated, and the attenuation regularities of vibration along the subgrade slope were revealed. The results indicate that the action of train moving loads on subgrade has obvious periodicity, and two bogies in the adjacent wagons can be regarded as one loading unit. The peak dynamic displacements at the subgrade shoulder obey normal distribution under the repeated loading of the loading units. The vibration frequency mainly distributes between 0 and 20Hz under the loading of heavy-haul trains. The vibration energy attenuates severely from the subgrade shoulder to the slope toe. The subgrade bed is influenced dramatically by dynamic loadings of trains, and moving train loads have little influence on the part below the subgrade bed. The research results can provide basis for the evaluation of instantaneous and long-term dynamic stability of subgrade, and offer guidance for simulating the train moving loads precisely in model test and numerical analysis to study the dynamic response of subgrade.