Current Status of CAS Team on Task A Step 0: Model Inception two-phase flowmodeling for the laboratory drying test – two-phase flow modeling for the laboratory drying test By Xiaoyan Liu, Chengyuan Zhang and Quansheng Liu Wuhan Institute of Rock and Soil Mechanics Chinese Academy of Sciences (CAS) October 20-23, 2008 Wakkannai, Japan DECOVALEX nd workshop & Task A Force Meeting

 Step 0: Identification of relevant processes and of Opalinus Clay parameters. Modelling of the laboratory drying test.  Step 1: Hydromechanical modelling up to the end of Phase 1.  Step 2: Hydromechanical modelling up to the end of Phase 2 using parameters backcalculated from step 1. Advanced features as permeability anisotropy, rock damage and permeability increase in the damaged zone may be considered.  Step 3: Hydromechanical and geochemical modelling of the full test. Conservative transport and one species considered.  Step 4: Hydromechanical and geochemical modelling of the full test. Reactive transport and full geochemical model (optional). Task A Research programme

Step 0 General model description Impermeable lateral boundaries 10cm 28cm

 General model description  Governing Equations  Code developement  Simulation results  Discussion  Conclusion  Next steps Outline

Based on three interacting continua General model description multiphase system: Liquid phase Gas phase Vapour Dry air Phase exchange Water

Governing Equations For liquid phase exchange evaporation or precipitation change volume change retention curve advection

Governing Equations For vapour change volume change Klinkenberg parameter phase exchange ordinary diffusion Slip Knudsen effect advection compressibility retention curve

Governing Equations For dry air No phase exchange Coupling scheme (1)Phase exchange (2)Saturation-Suction (3)Different mobility (advection and diffusion effects) of two gas

Code Development FEM solver : FRT-THM (Developed for Task D of Decovalex-THMC) FEBEX conception model Bentonite buffer Bentonite buffer Thermal expansion Thermal expansion Permeability change Permeability change Swelling No boiling Unsaturated / Saturated volcanic rock / crystalline boiling / no boiling no buffer / buffered YMP DST / FEBEX YMP DST conception model Permeability change Permeability change Drift with air Boiling Thermal expansion Thermal expansion Dry-out (for Task A of Decovalex-2011) Modified FRT-THM

0.1m D=0.1m Step 0 Inception simulation Boundary conditions FEM meshes: Geometry, Grid Design and Boundary Conditions H=0.28m Top Bottom Lateral no flux no flux 0.28m vapour & air, no water No-flux boundary forwater vapour vapour dry air 3D 2D

Variables & Parameters Step 0 Inception simulation (Munoz, 2001) 0.40 (in our work) 0.165

Boundary condition RH = *exp(day*24/ )+39.59

Step 0 Simulation results pv time= days Dry air pressure pa Vapour pressure pv Total gas pressure pv+pa 142 days days days days Water pressure pl Pressures profile

Comparison with Measured Data Step 0 Simulation results

Comparison with calculation by (Munoz, 2001) Step 0 Simulation results by (Munoz, 2001) Our work

Comparison with calculation by (Munoz, 2001) Step 0 Simulation results by (Munoz, 2001) Our work

Discussion (1) Influence of relative permeability k rl 142 days 21 days 99 days

Discussion (2) Influence of Discussion (2) Influence of Relative Humidity (RH)

Conclusion  Simulation on the laboratory drying test seems good. Preliminary compare to test data and the calculation using code_bright show that they match well.  We must do more calibration and benchmark test on our model, especially to make sure the parameters are correct and model work well.

Next step 1.To consider coupled mechanical processes (swell & shrinkage effect; Damage of the material ) 2. Step from 0 to 1.

Thank you for your attention