Research purposes: With seasonal frozen soil regions increasing passenger line engineering, security and stability of its subgrade has become an important factor affecting driving safety. The freeze-thaw cycles destroys the railway subgrade frequently in seasonal frozen soil regions. We coupled the temperature field with deformation field, and analysed the influence of how the thermal effects to the subgrade deformation. We also predicted the temperature field’s change and the deformation trend in subgrades many years later. It will provide reliable technical support to subgrade frost heaving protection.
Research conclusions: (1)In seasonal frozen soil regions，the subgrade’s maximum frost depth appears ahead of time， it will decrease when the negative temperature period becomes shorter. The subgrade deformation is less than 15 mm under the effect of the temperature and force fields. It meets the settlement control standard requirement. (2)The fillings have no frost heave or slight frost heave，which meets the negative temperature requirement in seasonal frozen soil regions. (3)Under the effect of temperature，there is no frost heave disaster in the subgrade during the 20 years’ service time. (4) The paper provides the valuable reference to the study on subgrade thermo-mechanical coupling in the freeze-thaw cycles，has great significance in the development of subgrade anti-frost techniques in seasonal frozen soil regions，and also provides the theoretical evidengce for the construction of China's railway passenger line in seasonal frozen soil areas.
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