Modelling and simulation of pavement drainage

Abstract

ABSTRACTThe development of a numerical model to describe pavement surface runoff by a system of non-linear hyperbolic partial differential equations enables the analysis and prediction of safety-relevant road design and construction. Aquaplaning risks could be minimised as well as damages to the road surface geometry prevented. The hydromechanical approach presented in this article by a two-dimensional Pavement Surface Runoff Model (PSRM) based on the depth-averaged Shallow Water Equations – in contrast to empirical models – represents a general simulation. PSRM includes features like the treatment of an irregular topography or the possibility to treat different surface textures. The model enables the calculation of water depths. Discontinuous solutions to the underlying equations are numerically gained by applying Riemann solvers with Godunov methods to compute approximate intercell fluxes over the discretised problem using Finite Volume Methods. The Harten–Lax–Van Leer (HLL) Riemann solver was chosen to calculate the intercell fluxes. Simulation examples show the wide range of possibilities to describe real pavement surface runoff problems, for example junctions and superelevation transitions. Flow resistance is modelled with the Darcy–Weisbach equation by considering the pavements mean texture depth (MTD) as a variable parameter. In order to take into account the pavement surface drainage capabilities due to infiltration processes in porous surface layers, a coupled three-dimensional numerical formulation enlarges the macroscopic PSR Model. The saturation of the porous surface geometry and the infiltration velocities by Darcy velocities under consideration of interface conditions on the interface between free flow on the road surface and drainage into the porous structure are implemented within an emerging hydromechanical numerical model.