On the Theoretical and Numerical Modelling of Unsaturated Soil

In this contribution, unsaturated soil is treated within the framework of the Theory of Porous Media (TPM). Therein, unsaturated soil can be described by a triphasic model consisting of a materially incompressible, elasto‐plastic or elasto‐viscoplastic solid skeleton, a viscous, materially incompressible pore‐liquid (water) and a viscous, materially compressible pore‐gas (air). The interaction between the solid skeleton and the pore‐fluids are taken into account by a capillary‐pressure‐saturation relation and a Darcy‐like filter law including relative permeabilities to consider the interaction between the two pore‐fluids. The resulting system of strongly coupled differential‐algebraic equations is solved for a gravity driven initial‐boundary‐value problem by the finite element tool PANDAS.