Effects of Static and Dynamic Loads on Frost Heave Deformation of Coarse-Grained Subgrade Soil in Cold Regions

With the rapid development of high-speed and heavy-haul railways in cold regions, understanding the influence of external loads on the frost heave behavior of subgrade fillings is of great importance. In this study, one-dimensional frost heave experiments were conducted on Group A coarse-grained soil under different static and dynamic loading conditions. The effects of upper plate freezing temperature, load magnitude, load frequency, and water supply (closed and open systems) were systematically investigated. The variations in internal temperature, frozen depth, frost-heave deformation, and post-freezing water content distribution were analyzed. The results indicate that external loads exert a certain inhibitory effect on frost-heave deformation of coarse-grained soil. Upper plate freezing temperature and load magnitude were identified as key factors influencing frost heave behavior, while load frequency had little effect. With decreasing upper plate freezing temperature, both frozen depth and frost-heave deformation increased. The frost heave ratio decreased with increasing load magnitude. Compared with fine-grained soil, coarse-grained soil exhibited shorter frost heave growth periods (about 3–5 h) and less pronounced ice lens formation. In addition, the water content in the frozen portion increased slightly, while that in the unfrozen portion decreased. These findings provide valuable insights for evaluating the stability of railway subgrades and optimizing design parameters in cold-region engineering.