Numerical modeling of post-flood water flow in pavement structures

Water infiltration through pavement structures as a result of flooding and/or extreme rainfalls, can adversely influence the bearing capacity of the pavement and lead to its premature failure. Since the entire pavement system will not be always in saturated state, the post-flood water movement throughout its granular layers should be formulated based on unsaturated flow principles. This study is aimed at developing a practical numerical model for simulating the partially saturated water flow in pavements caused by surface infiltration. To this end, available numerical methods and software packages are evaluated based on the relative merits of availability and computational rigor. The selected method is validated with published data. Existing correlations are used to reduce the number of inputs required for modeling. Subsequently, a parametric study is carried out to investigate the influence of material properties, such as aggregate gradation, and environmental conditions, such as rainfall intensity and duration, on the pavement's response. Special cases, such as anisotropic material and clogged drainage are also modeled. This study provides an insight into the hydraulic behavior of pavement structures subjected to severe precipitation. In addition, this model establishes a solid basis for subsequent structural analyses to fully understand the behavior of inundated pavements under traffic loadings.