An unsaturated hydro-mechanical modelling of two in-situ experiments in Callovo-Oxfordian argillite

• Experimental data synthesis for retention curve and relative permeabilities for COx.
• Models for fluid transfers in unsaturated conditions are important.
• Determination of retention curve and gas permeability close to saturation is needed.
• An accurate model for fluid transfers between rock mass and surrounding air is needed.
• Dissolved gas plays a significant role on the compressibility of liquid phase.

The unsaturated behaviour of Callovo-Oxfordian argillite is investigated through the modelling of 2 in-situ experiments. The first test studies the influence of ventilation in a gallery on the hydro-mechanical behaviour of the rock mass. The second test consists in a gas injection in the rock mass from an experimental borehole. A hydro-mechanical model is described and used in the modelling of the experiments. A review of the main hydro-mechanical parameters of argillite is presented. The numerical results highlight the need of a flow boundary condition reproducing the fluid transfers between the surroundings and the rock mass. The influence of dissolved gas on the compressibility of the liquid phase is also emphasised.