Thermal insulation performance and dynamic response of anti-freeze subgrade of high-speed railway in seasonally frozen regions

In order to counteract the adverse effects of seasonally frozen regions, measures need to be taken to insulate highspeed railway subgrades and implement anti-freeze structures. The present study delves into this topic by analyzing the thermal-mechanical behaviors of railway subgrade through on-site measured data. Then, using the hydrodynamic theory, a model of frozen soil with Multi-physical field coupling is built, on which the temperature field and frost heave development of six different subgrade structures are explored, and produces a vehicle-tracksubgrade coupling dynamic model that is used to calculate the dynamic performance of vehicles and the dynamic response transfer between subgrade layers under the influence of different anti-freeze subgrade structures. The results show that the subgrade structure built using concrete insulation (asphalt concrete (AC) or cellular concrete (CC)) + cement stabilized crushed stone (CSCS) + polyurethane (PU) panel mitigates the impact of external air temperatures and internal cooling, helping to reduce the maximum frost heave while simultaneously achieving improved thermal insulation. Further, these anti-freeze subgrade structures also bolster the safety and stability of high-speed railway vehicle operations. Therefore, it is suggested that the "concrete insulation layer + CSCS layer + PU panel" structures be utilized as a reference during the design of subgrade structures in seasonally frozen regions.