中文摘要：

为研究高速铁路有砟道床因反复承受高频率的列车荷载作用而劣化及累积变形的规律,利用离散元分析软件PFC并考虑道砟颗粒的真实几何形态,建立高速铁路有砟道床三维离散元模型,模拟分析不同频率、不同幅值循环简谐荷载作用下道床的累积变形,并通过统计分析道砟颗粒的重排行为,从细观层面探讨荷载频率对道床累积变形行为的影响机理。开展高速铁路有砟道床的室内实尺模型累积变形试验,验证道床离散元模型的合理性和模拟结果的可靠性。结果表明：在相近的荷载工况下,模拟分析获得的道床累积变形结果与实尺模型试验结果较为吻合;循环简谐荷载的频率低于15 Hz时,道床的累积变形主要由道砟颗粒间的相对接触滑动引起,但累积变形及其增长速率均不大;当荷载频率提高至20 Hz以上时,道床的累积变形及其增长速率随荷载频率的提高而快速增大,且其主要原因是道砟颗粒发生了剧烈转动。

英文摘要：

In order to investigate the laws for the deterioration and accumulated deformation of high-speed railway ballast bed under repeated high frequency train load,a three dimensional discrete element model（DEM model）of high-speed railway ballast bed was established using the discrete element analysis software PFC and considering the real geometry morphology of ballast particles.With this model,the accumulated deformation of ballast bed under cyclic harmonic loads with different frequencies and amplitudes was simulated and analyzed.The influence mechanism of loading frequency on the accumulated deformation of ballast bed was also discussed from meso-scale through the statistical analysis on the rearrangement behavior of ballast particles.The accumulated deformation test of high-speed railway ballast bed was carried out using a full-scale laboratory test rig to validate the reasonability and reliability of the DEM model.Results indicate that under similar load conditions,the results of ballast accumulated deformation obtained from DEM simulation are basically consistent with full-scale model test results. When the frequency of cyclic harmonic load is lower than 15 Hz,the ballast accumulated deformation is mainly induced by particle relative contact sliding,but the accumulated deformation together with its increasing rate are relatively small.When the loading frequency is increased to 20 Hz,the ballast accumulated deformation and its increasing rate increase remarkably with the increase of loading frequency,which is mainly caused by the violent rotation of ballast particles.