<p>Addressing the oversight of neglecting time interval effects in previous studies on the dynamic plastic strain of soil in karst ground collapse areas under train-induced environmental vibration, a series of dynamic triaxial tests were designed, comparing continuous loading with loading that incorporated time intervals. These tests considered the influence of loading conditions such as dynamic stress levels, loading frequencies, and interval durations on the cumulative plastic deformation of red soil. Based on the time-hardening rule, a “stable” soil sample cumulative plastic strain model was revised to account for interval time effects, predicting the permanent dynamic deformation of the red soil overlaying karst collapse zones. The study revealed that the presence of time interval effects “weakened” the dynamic response to vibrational loads, with residual strain decreasing more significantly as the time interval increased. An increase in dynamic stress amplitude notably elevated the level of cumulative plastic deformation, and the cumulative plastic impact varied with loading frequency, showing a rapid increase in the early stages of loading followed by stabilization. The revised hyperbolic prediction model for cumulative plastic strain, which accounts for interval time effects, demonstrated good prediction performance under various loading conditions, accurately predicting the permanent deformation of red soil overlaying karst collapse zones in train-induced environmental vibration fields. The findings of this study are significant for understanding the long-term dynamic stability of red soil overlaying karst collapse zones under intermittent train loads and provide technical guidance for predicting karst collapse hazards in railway engineering due to train-induced environmental vibrations.</p>