A dual porosity model for infiltration processes in fractured porous swelling soils

Dual-porosity, dual permeability and multi-region models (based on different interacting regions) simulate the behavior of fractured or heterogeneous soils and make it possible the analysis of water infiltration through unsaturated zone. Most of the existing literature models do not take into account of shrinking-swelling dynamics of clayey soils that cause the closure of fractures during water flow and the retaining water. For this purpose it has been proposed an “evolving” dual-porosity model whereas fractures behave like pipes subjected to progressive narrowing due to the swelling matrix as consequence of water content increase. The model has been used to study the differences among infiltration process in consequence of rainfall of severe and low intensity. It has been studied also the effect of the presence of at a certain depth of a layer of high permeability taking into account the effect of a capillary barrier between a low permeability and the higher permeability layers. The application of the model to a loamy fractured soil superimposed to a coarse layer and the results of sensitivity analysis are also introduced.