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D2011 Project

D2011 Project. Wakkanai, Japan, October 20-23, 2008 Task A - STEPS 0/1. CEA-IRSN Results Alain MILLARD, Frédéric DELERUYELLE. Contents. Introduction Step 0 Theoretical model and hypothesis Material parameters Drying test Model setup Results Step 1 Hypothesis Preliminary results

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D2011 Project

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  1. D2011 Project Wakkanai, Japan, October 20-23, 2008 Task A - STEPS 0/1 CEA-IRSN Results Alain MILLARD, Frédéric DELERUYELLE

  2. Contents • Introduction • Step 0 • Theoretical model and hypothesis • Material parameters • Drying test • Model setup • Results • Step 1 • Hypothesis • Preliminary results • Conclusion

  3. Introduction • Step 0 : Preparation to VE calculation • Analysis of supplied reports • Simple laboratory experiment : Drying test • Use of Floria et al’s report for modelling • Step 1 : Calculation of VE : phases 0 and 1 • Preliminary analysis • Same model and material properties

  4. Theoretical model and Hypothesis • Isothermal unsaturated poroelastic model • pores filled by liquid water and gaz ( air + vapor) • gaz pressure assumed constant ( Richard’s model) Water mass balance : - vapour mass negligible compared to liquid water - ρl constant - liquid water flux given by Darcy’s law: =>

  5. Theoretical model and Hypothesis Capillary pressure curve (Munoz et al, 2003) : modified Van genuchten’s law : Fit on drying paths λ=0.128 Ps = 700 MPa λs= 0.273

  6. Theoretical model and Hypothesis Intrinsic permeability (Munoz et al, 2003) : Water relative permeability (Munoz et al, 2003) : Van genuchten’s law : Proposed parameters : φ0 = 0.16 K0 = 2. 10-20 m2 λ’ = 0.68

  7. Theoretical model and Hypothesis Momentum balance : Behavior law : Isotropic case:

  8. Material parameters

  9. Drying test • 3 samples of Opalinus clay : MA, MB, MC • Drying in a chamber with controlled T and Hr • Continuous measure of weight loss • Water content profiles at 21, 99 and 142 days • Cylindrical samples φ=101 mm, h=280 mm • Bedding planes parallel to samples axis • Drying from upper face • Unconstrained lateral displacements

  10. Drying test

  11. Drying test

  12. Drying test

  13. Model setup • H behaviour is ~ 1D => axisymetric model • Isotropic properties • Refined mesh close to drying boundary • Constant temperature T=30°C • Hr either constant (33%) or linearly variable ( from 25% to 45%) • Different permeabilities considered • Computer code : Cast3M (CEA)

  14. Initial and boundary conditions Pl= Patm + (ρl R T /Mv) ln Hr Hr = 33% or Hr(t) T(0) = T(t) = 30°C W(0) = 7% φ (0) = 0.16 Φl . n = 0

  15. ResultsK0 = 2.0 10-20 m2, Hr = 33% Change in mass with time Water content profiles

  16. ResultsK0 = 1.96 10-20 m2, Hr = 33% Change in mass with time Water content profiles

  17. ResultsK0 = 1.96 10-20 m2, Hr = Hr(t) Water content profiles Change in mass with time

  18. Step 1 – VE Experiment Phases 0,1 Phase 1

  19. Step 1 – Hypothesis • 2D plane strain model • Isotropic properties • Isotropic in-situ stresses • Constant temperature T=15°C • Prescribed Pl from Hr at tunnel wall • Same material properties as for Step 0 • Phases 0 and 1 : calculation over 2123 days

  20. Mesh 130 m

  21. Initial and boundary conditions σ = -3.2MPa, Pl = 1.21MPa Pl = Hr (t) σ (0) andPl (0) affine in z Sl (0) = 1 φ (0) = 0.16 U . n = 0 Φl . n = 0

  22. Pore pressure from 65 cm to 69 cm

  23. Hr from 65 cm to 69 cm

  24. Relative humidity 1,90 m 100 % 1,40 m 1,00 m 0,90 m 70 % 0,67 m 40 %

  25. Relative displacement 0.2 mm 0. -1.5 mm

  26. Initial water pressure 2 MPa 0. -12 MPa

  27. Water pressure 2000 KPa 2.80 m 2.40 m 0. 2.10 m 1,70 m -1500 KPa

  28. Conclusion • Step 0 : • H behaviour dominates • Fair H predictions using parameters proposed • Hr = constant is a reasonnable hypothesis • Possible improvement: evaporation condition • Step 1 : • Preliminary results • Improvements : Phase 0 and boundary condition in tunnel

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