Permanent deformation of subgrade induced by long-term truck traffic loading in seasonally frozen regions

To determine permanent deformation and its accumulation characteristics of subgrade induced by long-term traffic loading in seasonally frozen regions, a calculation method is proposed based on the accumulative strain empirical of subgrade soil under cyclic loading. Then, a finite element model of base-subgrade-foundation was built, and the effects of truck type, rear-axial loading, running speed and the depth of subgrade on the stress ratio and permanent deformation in the normal and spring-thawed period are analyzed. The calculated results show that: the stress ratio decreases with the increasing of depth in the normal period, and the stress ratio in thawed soil is greater than frozen soil and normal soil. Six-axis truck could produce more permanent deformation than other four types truck. The stress ratio and permanent deformation increases with the increasing of the rear-axis loading and the thickness affected by freeze-thaw action. Stress ratio and permanent deformation decreases with the increasing of running speed. Furthermore, a prediction formulation of subgrade permanent deformation is proposed based on the above calculation results.