Analysis on stress level of subgrade under cement concrete pavement

Factors affecting the stress level of subgrade were investigated through systemic parameter analysis, and then a 3D finite element model was established and used for load stress analysis. For typical cement concrete pavement structure, the stress of subgrade was calculated under all kinds of gear weights and configurations. Analysis result indicates that the subgrade workaround is deepened and the stress level in the region is raised with the increasing of the gear weight and the number of axis. The stress induced by multi-axis was overlapped in the deep-seated subgrade. The stress state of subgrade was calculated by adding the at-rest pressure to the load stress which was computed by finite element analysis. The statistical result of stress state illustrates that the maximum and minimum principal stress range in 30~70 kPa and 10~40 kPa respectively, and the principal stress ration is fluctuated between 1.9 and 6.0. The magnitude of stress in subgrade is increased by 10 kPa when the applied load enhances from 100 kN to 200 kN, which impacts the mechanical behavior of subgrade dramatically. Thus, it is needed to consider the stress-dependent behavior of subgrade in pavement design.