The realistic simulation of the train dynamic loading is essential to the study of the dynamic behaviors and long-term stability of the railway subgrade. Considering the loading intermittence caused by the time interval between adjacent trains and the increasing dynamic stress response of the subgrade caused by the increasing axle load and running speed of trains, a series of dynamic triaxial tests with single-stage and multi-stage intermittent cyclic loading were performed. The results show that the existence of the intermittent stage improved the resistance of samples to cyclic loading and thus reduced the permanent strain, and the initial small dynamic stress under multi-stage loading also effectively reduced the accumulation of permanent deformation under the subsequent large dynamic stress. Based on the time-hardening approach, a prediction model for the permanent strain was proposed to consider the influence of loading intermittence and multi-level dynamic stress, and this model can predict the permanent strain under single-stage and multi-stage intermittent cyclic loading well. The research results can provide guidance for further understanding of the deformation characteristics and settlement prediction of railway subgrade under actual train loading.

列车动载荷的真实模拟对于研究铁路路基的动力特性和长期稳定性至关重要。考虑到相邻列车之间的时间间隔所引起的载荷间断性以及由于列车的轴载荷和行驶速度的增大而引起的路基动应力响应的增大，进行了一系列单阶段和多阶段间歇循环载荷的动态三轴试验被执行。结果表明，间歇阶段的存在提高了样品对循环载荷的抵抗力，从而减小了永久应变，多阶段载荷下的初始小动应力也有效地减小了随后大动应力下的永久变形的积累。根据时间强化方法，提出了考虑应变载荷间歇性和多级动应力影响的永久应变预测模型，该模型可以很好地预测单阶段和多阶段间歇循环载荷下的永久应变。研究结果可为进一步理解实际列车荷载下铁路路基的变形特征和沉降预测提供指导。