Impact of double porosity flow on hydrologically driven failure of a hillside slope

Abstract:

Soil deposits in hillside slopes often exhibit two dominant porosity scales, often referred to as the macropore and micropore scales. Fluid flow through this type of soils involves preferential flow through the macropore region and fluid storage in the micropore region. An explicit treatment of the two porosity scales, known as double porosity formulation, is necessary for a more realistic description of the hydromechanical behavior of this type of soils. In this work, we investigate how double porosity modeling of fluid flow and deformation could impact the ensuing hydromechanical responses of a hillslope under rainfall infiltration. For this purpose we use a hydromechanical continuum modeling approach developed in previous work by the authors and extend it to accommodate double porosity modeling by employing a recently developed hydromechanical framework along with a stabilized finite elements technique that allows the use of lower-order mixed finite elements for improved computationally efficiency. The numerical results demonstrate that preferential flow can be captured by the double porosity formulation, leading to a different slope failure mechanism than what is predicted by an equivalent single porosity formulation.