Deformation characteristics and cumulative plastic strain prediction model of saturated silty filler under intermittent heavy-haul train loads

The train loading acting on subgrades is concentrated within specific duration, exhibiting an intermittent cyclic loading characteristics in time domain. However, soil deformation behaviour under such a loading pattern has not been adequately understood. Dynamic triaxial tests were implemented to facilitate the investigation of saturated silty filler deformation evolution experiencing intermittent cyclic loading. The results provide new insights incorporating: a) the presence of load intermittency alters the deformation behaviour compared with continuous loading condition, leading to a slower development of cumulative plastic strain and a more stable soil fabric; b) increasing dynamic stress drives a transition of deformation behaviour from stable to critical and eventual failure, whereas greater confining pressure limited the growth of plastic strain; c) rebound strain and volumetric strain were observed during intermittent phases, the proportion of rebound strain to cumulative plastic strain diminishes with rising dynamic deviator stress level, whereas volumetric strain shows corresponding increase and d) a predictive framework for cumulative plastic strain was proposed, incorporating both equivalent initial plastic strain and the normalised plastic strain growth rate. Verification against experimental data confirmed its robustness, and the comparative assessment revealed superior performance compared with four existing predictive approaches.