Abstract:Frost heave and thaw subsidence is the main disease of subgrade in alpine meadow area, and it is also an important problem that scientific researchers and engineers need to solve urgently. For the subgrade in the seasonal freezing zone, the creep effect makes the frost heave deformation of the subgrade more complex, so it is particularly important to establish a mathematical model of frozen soil considering creep damage.The frozen soil is regarded as a nonlinear elastic body, and the mathematical model of frozen soil under the coupling of three fields is established from the point of view of water separation field, temperature field and stress field, respectively, based on the differential control equation of each physical field and the relationship equation between them. Based on the mathematical model, the subgrade in alpine meadow area is calculated. It is found that the maximum freezing depth of subgrade is 1.2 m below the surface of subgrade, and the maximum depth of freezing front is 0.6 m below the top of subgrade, and the stress concentration is easy to occur at the top angle of left and right subgrade, the junction of new and old subgrade fill and the inflection point of slope foot. The maximum horizontal displacement is about 6.44 mm and the maximum vertical displacement is about 15.8 mm, which occurs at the junction angle between the two sides of the slope and the top of the subgrade. The measures to prevent frost heave should be strengthened on both sides of the slope and at the junction angle of the top of the subgrade.