Modeling Water Flow Patterns in Flexible Pavements

Abstract

Most road design models do not explicitly account for moisture transport mechanisms in roads, even though it is well known that water content plays an important part in the deterioration of roads. The Swedish National Road Administration aims to improve the current situation by supporting the development of models that eventually can provide a better and more complete description of the road and environment system. The applicability of hydrological theories and methods to the road and environment system was investigated. Particular attention was paid to flow patterns inside the road as affected by capillary barriers and generated by mechanisms of surface runoff, followed by infiltration into cracks, and the embankment. Particle tracking was used to investigate the effect of rain intensity, precipitated amount, or fracture conductivity on the flow patterns. Changes in rain intensity had a small effect on flow patterns, but velocities were higher for larger rain intensities. Both changes in precipitated amount and fracture conductivity controlled the appearance of the flow patterns, but capillary barrier effects were limited. The numerical code used proved to be mostly appropriate in describing the relevant processes.