Assement of Flexible Pavement Foundation’s Vulnerability Due to Heavy Rainfall in Minnesota

Climate change has led to heavy rainfall in the Midwestern region of the USA causing damage to flexible pavement foundations. This study assesses the vulnerability of pavement foundations to such heavy rainfall in Minnesota. PLAXIS 3D, a geotechnical finite-element analysis tool, was used for creating rainfall scenarios and simulating moisture fluxes in pavement layers. The results obtained from the PLAXIS 3D model were validated using moisture and rainfall data collected from sensors installed at low-volume roads and weather stations at the Minnesota Road Test Facility (MnROAD) of the Minnesota Department of Transportation. The reduced stiffness of the pavement foundation was quantified by reduction of the resilient modulus of the corresponding layers. In this study, the Mechanistic-Empirical Pavement Design Guide (MEPDG) equation was used to predict the resilient modulus of base aggregate at any level of saturation and to determine the effect of moisture changes resulting from heavy rainfall. The analysis showed that greater precipitation intensity increased the moisture flux and reduced the stiffness of the base aggregate layer. A negative linear trend of stiffness reduction due to heavy precipitation was also observed in the analysis. Such reduced stiffness in a pavement foundation could make it more vulnerable to traffic loads and shorten its lifetime.