A multiphase approach for a unified modelling of fully and partially saturated porous materials by considering air dissolved in water

A unified mathematical model for the hydro-thermo-mechanical behaviour of saturated and partially saturated porous media is developed to analyze saturated/unsaturated porous media considering the effects of air dissolved in water. Physics of air dissolution and water cavitation in porous media, as well as different numerical techniques used for modelling the transition between fully and partially saturated state, are briefly discussed. The model equations are discretized by means of the Finite Element method. A correspondingly updated code is used to analyze two examples. It is shown that considering the dissolved air had a small influence on the results of numerical simulations both for water outflow due to gravity forces (Liakopoulos test), and the fast fluid flows and cavitation accompanying water desaturation in the strain localization zone during compression test of dense sands. However, the procedure allows for unified modelling of the partially and fully saturated media, without application of any ‘unphysical’ numerical technique.