Modelling and estimation of water infiltration into cracked asphalt pavement

The present method used to estimate water infiltrating into the pavement of highway is regional and less representative. Based on the flow theory in porous media and Poiseuille cubic law in cracked media, a model was established to quantify the water balance between surface course and the drainage layer in the pavement of highway to estimate the pavement infiltration rate (PIR). Through mathematical derivation of governing equation of water balance in the pavement system, an analytical solution was obtained to express the PIR, which comprehensively takes crack length, crack open width, crack interval, thickness and permeability of structure layers into consideration. The quantitative analysis results showed that the PIR is proportional to crack open width, crack length, drainage layer thickness and permeability of surface course; on the contrary, the PIR is inversely proportional to crack interval distance, surface course thickness and permeability of the drainage layer. The crack property affects the PIR in terms of improving the water entry, while various thicknesses of pavement structure layers and hydraulic conductivities result in a different hydraulic gradient between the top and bottom of surface course thereby leading to a different PIR.