Dynamic behaviors of coarse granular aggregates in high-speed railway subgrades

Abstract

With the increase in the running speed and axle load of trains, there has been a greater demand for high-speed railway (HSR) subgrades. Coarse granular aggregates are suitable materials for the HSR subgrade filler. Hence, the study of the dynamic characteristics of coarse granular aggregates is important for the safe operation of trains. In this study, a dynamic triaxial test apparatus was used to investigate the dynamic features of these aggregates under different dynamic amplitudes, confining pressures, fine particle contents, and water contents. The characteristics of the hysteresis loops, dynamic resilient modulus, and cumulative plastic strain during the cyclic loading of the soil were studied. The results illustrate that the hysteresis loop becomes more compact with an increase in the dynamic stress amplitude. The changing law of the dynamic resilient modulus depends on factors such as fine particle content, confining pressure, dynamic amplitude, and water content. Meanwhile, the cumulative plastic strain features are influenced by the critical dynamic stress and applied dynamic stress under the corresponding conditions. Based on the experimental results, a prediction model for the cumulative plastic strain considering the stable, critical, and failure types was proposed. Thus, the plastic strain at more loading cycles can be predicted. These results can help in the design of subgrade structures and maintain the daily safe operation of the HSR.