Status report on Step1 of Task A, DECOVALEX-2011 modeling for Ventilation Experiment –modeling for Ventilation Experiment By Xiaoyan Liu, Chengyuan Zhang and Quansheng Liu Wuhan Institute of Rock and Soil Mechanics Chinese Academy of Sciences (CAS) April 20-23, 2009 G, Korea DECOVALEX 2011 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

Ventilation Experiment step 0 to 1 1.To consider coupled hydro-mechanical processes (swell & shrinkage effect) Step 1 General model description

 General model description  Governing Equations  Step 1 Simulation results  Conclusion  Discussion  Future work Outline

Based on three interacting continua General model description of 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 of Flow model (1)Phase exchange (2)Saturation-Suction (3)Different mobility (advection and diffusion effects) of two gas

Governing Equations For solid deformation Porous pressure saturation and heat dilatancy

Step 1 modelling Geometry, Grid Design and Boundary Conditions Experimental condition in MT test section 200m 34 5 m 10 0m 18 9m 1.3m Groundwater table MicroTun nel

Step 1 modelling Geometry, Grid Design and Boundary Conditions Experimental condition in MT test section These four Boundaries:

Step 1 modelling Geometry, Grid Design and Boundary Conditions Experimental condition in MT test section No Water flow

Step 1 modeling Experimental Conditions Experimental condition in MT test section

Step 1 Variables & Parameters used in simulation (Munoz, 2003) 0.40 (in our work) Hydraulic properties: Variables & Parameters in Step 0

ParameterValue Solid grain density Kg/m Moisture swelling coeff. [-] 0.11*10 -4 Poisson ratio [-] 0.27 Young ’ s Modulus [GPa] 6 Mechanical and hydro-mechanical properties: Step 1 Variables & Parameters used in simulation

Step 1 Simulation results 342 days experimental data of ventilation condition and simulation results of RH

Step 1 Simulation results Evolution of calculated rock outflow flux

Step 1 Simulation results accumulated water mass out of rock wall

Step 1 Simulation results Calculated total accumulated water mass out of rock wall during Phase 1 and its comparison with the monitored data in desaturation period

Step 1 Simulation results Simulation results for evolution of porous water pressure

Step 1 Simulation results Simulation results for evolution of calculated water pressure in some locations around the test section (distance of 0.65m, 0.67m, 1.3m, 2m, 3m and 5 m from MT center)

Step 1 Simulation results Simulation results for evolution of water saturation in rock near MT

Step 1 Simulation results Simulation results for evolution of water saturation in rock near MT

Step 1 Simulation results Rock displacements around the test tunnel after excavation

Conclusion  Simulation on the ventilation experiment of Step 1 seems good.  In the work of Step 0 &Step 1, getting started and familiarize with the problem developing our simulation models and numerical code conducting a comparative analysis of coupled (T)H and (T)HM modelling making comparison with experimental observations making comparison with other teams’ calculation results  We must do more calibration and benchmark test on our model, especially to make sure the parameters are correct and model work well.

Discussion  Results are very sensitive to intrinsic permeability, relative permeability and capillary pressure.  Detailing input information for model is important, e.g. parameters of properties, initial and boundary conditions.  Sensitivity analysis of vapor diffusion, permeability, permeability saturation dependence, retention curve will be benefit to improving models for complex coupled problem.

Future work 1.Damage and microcracking due to hydromechanical and chemical effects should be involved in modeling work. 2.We should improve our model to deal with heterogeneous permeability field and to consider the anisotropical evolution of permeability induced by rock damage. 3.After the 3rd workshop, we will start work for the Step 2 to perform an advanced hydromechanical modelling up to the end of Phase 2 using parameters back- calculated from step 1.

Thank you for your attention