针对武广客运专线路堑红粘土在列车循环荷载作用下产生动变形及动力稳定性问题,利用疲劳动三轴试验,首次研究了循环荷载作用下原状结构红粘土动应变随振次的变化规律,获得了不同试验条下原状结构红粘土的临界动应力,并给出其估算公式.探讨了含水比、围压、固结比对临界动应力的影响. Aiming at the dynamic deformation and dynamic stability of red clay in RCC of Wuhan-Guangzhou Passenger Dedicated Line under the cyclic loading of train, the dynamic variation of undisturbed red clay with undulating load under cyclic loading was studied for the first time by the fatigue triaxial test. The critical dynamic stress of undisturbed red clay under different test conditions was obtained and its formula was given. The influence of water content ratio, confining pressure and consolidation ratio on the critical dynamic stress was also discussed.