Pavement mechanic response of sulfate saline soil subgrade section based on fluid-structure interaction model

It is a consensus that salt heaving and frost heaving are urgent and typical distress in the sulfate saline soil area. To further investigate the microscopic performance of pavement structure in this special area, Jinan-Dongying Freeway in Shandong Province is selected as a case study engineering and the mechanic responses under salt heaving, frost heaving and traffic loads were analyzed through the finite element (FE) Program (ANSYS). In this paper, the process of salt heaving and frost heaving was divided into 3 stages and FE models were established based on fluid-structure interaction (FSI) model. It is shown that under both effects of salt heaving and frost heaving, the tensile stress of asphalt surface course could be up to 96.75% of its tensile strength, which means its tensile strength was seriously inadequate; however, traffic loads could help to dramatically counteract effects of salt heaving and frost heaving, which could decrease 40-80% of the tensile stress in asphalt surface course. It is also shown that in Jinan-Dongying Freeway effects of salt heaving had slightly larger effects on pavement compared with that of frost heaving, probably because salt heaving occurred from the top to the bottom of subgrade. However, as a whole, in sulfate saline soil area, compared with general area, crack resistance of asphalt courses and foundation treatment should always be strengthened.