翻浆状态下无砟轨道路基动力响应特征模型试验研究

高速铁路无砟轨道基床翻浆是一种特殊的路基新型病害,影响高速铁路运营的舒适性和安全性,为分析无砟轨道路基基床翻浆对路基动力响应特征的影响,开展无砟轨道-路基基床大比例模型试验。试验结果表明:基床翻浆状态时,在动荷载下底座板对基床表层产生瞬态碰撞,使得基床表层土动压力随动荷载加载次数的增大而逐渐增大,沿深度衰减速率变快;基床翻浆改变了基床表层与底座板之间的动力传递特性,竖向振动加速度比值增大了1. 95倍以上,动位移比值增大了4. 56倍以上,振动响应从底座板传递至基床表层衰减梯度增大;基床表层翻浆不断恶化,会降低基床表层对底座板的支承能力,致使无砟轨道-路基基床动力响应加剧。

Model Experimental Study on Dynamic Response Characteristics of Ballastless Track Subgrade Subject to Mud Pumping

Mud pumping is a special new defect of ballastless track subgrade of high-speed railway,and it has remarkable effects on the comfort and safety of high-speed railway operation. In order to analyze the influences of mud pumping of subgrade bed on the dynamic characteristics of ballastless track subgrade,a large-scale model test of the ballastless track and subgrade bed was carried out. The results show that when the top layer of the subgrade bed suffers mud pumping,the base plate has a transient impact on the top layer of the subgrade bed under the dynamic load,causing the soil dynamic pressure to increase with the increase of the loading times and the attenuation rate along the depth becomes faster. Mud pumping can change the dynamic transmission characteristics between the top layer of the subgrade bed and the base plate. Compared with the top layer of the subgrade bed without mud pumping,the vertical vibration acceleration and displacement ratios of the base plate to seal layer of the subgrade bed are increased by more than 1. 95 and 4. 56 times respectively. The attenuation gradient of the vibration response from the base plate to the top layer of the subgrade bed increases. Mud pumping deteriorating under dynamic loading can reduce the bearing capability of the top layer of the subgrade bed to the base plate,which can result in vibration intensification of the ballastless track and subgrade bed.