FEM-based numerical simulation of water flow through a road shoulder structure

Water infiltration and its effects on road structures is a topic of great interest in civil engineering. Water is one of the primary factors which affects the mechanical function of roads. Road structures are more often found in unsaturated conditions as opposed to saturated ones. Under unsaturated conditions water flow is primarily by capillarity, while under saturation gravity is the primary force causing water movement. Moreover, under unsaturated conditions the equations describing water flow into soils are highly nonlinear, showing a higher difficulty in its numerical solution. At present there is a limited volume of literature on the hydraulic properties and numerical simulation of water flow in road structures under unsaturated conditions. This paper presents experimental data and nonlinear numerical simulations using the finite element method (FEM) to analyze the water infiltration through a road should structure in unsaturated conditions. Results show that the shoulder section evaluated in this study does not represent a zone of high water infiltration due to the low infiltration capacity of the materials evaluated, and that hydraulic properties measured in the laboratory can be successfully used in numerical codes for assessing water flow through road structures in future analysis. This work indicates that continuous rainfall events, even of low intensity, can cause more infiltration than a single rainfall event of high intensity.