Analysis of the performance of road subgrades using concepts of Pavement Mechanics

ABSTRACT The pavement is considered a system of multiple finite layers, subject to tensions, deformations and displacements from cyclical traffic demands. The foundation of the structure must have support capacity compatible with the intensity and frequency with which it will be requested. From this perspective, the present study evaluates the performance of four soils with different geological origins, usually found in road subgrades in the state of Rio Grande do Sul, based on the principles of Pavement Mechanics. The methodology applied in this study consisted of numerical simulations assisted by two computational programs: AEMC/SisPav and AASHTOWare Pavement ME Design. The mechanistic analyzes were performed to evaluate the soil response to resilient deformation and shear strength, important properties in the use of paving soils. The results showed that the resilient deformation has a preponderant role in the performance of the materials, since, for the analyzed soils, there is no evidence of shear rupture, both as a road subgrade material and as a foundation of low traffic pavements. This, however, does not rule out the hypothesis of high plastic deformations. Regarding the resilient deformation, it was also observed the inefficiency of the current flexible pavement design method, which does not consider the resilience modulus of the paving materials, resulting in the predominance of fatigue rupture, with the exception of the CB soil, which could lead to pavement to rupture by excessive wheel track rutting.