Etude des ouvrages de stockage souterrain de d

1
Etude des ouvrages de stockage souterrain de
déchets de haute activité

• ULg équipe de géomécanique
• SCK CEN / ULg 02/09/10

2
ULg Geomechanics team

• R. Charlier, Pr. O, chairman SAC Praclay
• F. Collin, Chercheur Qualifié FNRS
• S. Levasseur et B. François, Chargés de Recherche
  FNRS
• A. Dizier (FRIA), P. Gérard, S. Delvoie, B.
  Cerfontaine, doctorants
• JP Radu, F. Pascon, ingénieurs de recherche
• Labs team 4 people.

3
Research themes

• Geomechanics
• Rupture
• Thermo-hydro-mechanical coupling
• Numerical modelling LAGAMINE code
• Experimental investigations

4
Stockage géologique profond différents concepts

• 2 options
• Forages profonds creusés à partir de la surface
• Enfouissement dans des mines

5
The PRACLAY in-situ experiment comprises three
tests the GalleryCrossing Test, the Seal
Test and the Heater Test
6
Underground nuclear waste disposals

• Rock behaviour around disposals
• Mechanical behaviour
• Fluid transfers
• Heating / cooling effect
• Numerical simulation
• Clayey rocks URL Mol, Bure, Mont Terri

7
Fractures observed at Bure and HADES
COX
Slickenside
BC
8
Fracture traces observed on the excavation walls
COX
BC
9
Fractures pattern observed along borehole cores
in COX and BC
COX
BC
10
Typical herringbone pattern observed during
excavation in COX and BC
4 m
COX
BC
11
DZ as a preferential transport pathway

• DZ damaged zone, i.e. zone strongly modified by
  the mechanical loading
• Mechanical loading excavation, heating, gas
  generation
• Transport pathway fluid (liquid and gas) flow
  as radionuclide advective transport

12
Geomechanics coupled to fluid flow geomechanics
know-how

• Fluid pressure direct influence on mechanical
  state of stress Terzaghi / Bishop effective
  stress, net stress suction
• But few effect of geomechanics on fluid flow,
  unless changes in permeability
• Damage, permeability and stress distribution
  studies in Excavation Damaged Zone needed

13
DZ as a preferential transport pathway

• Describe the Damaged Zone
• Damage as a rather general concept
• Transport pathway considered based solely on
  fluid flow
• Basic question what is the permeability
  evolution related to damage

14
Chip formation experimental results (LML) and
numerical modelling (ULg)
15
Essais sur cylindre creux LMR EPFL V. Labiouse
16
Essais sur cylindre creux LMR EPFL V. Labiouse
17
MODÈLE NUMÉRIQUE / EXPÉRIMENTAL
Comparison between experimental data and
modelling (at the end of the second
phase) Experimental data show anisotropy
Radial evolution of the radial displacement
18
Modélisation de la localisation des déformations
¼ de cylindre creux
Localisation des déformations de cisaillement
Déplacements
7 mm
42 mm
Déplacement maximum 3.2 mm
avec
et
19
EDZ permeability distribution
Coupling Mechanic Permeability
Changes of permeability 5 order of magnitude
Vertical drilling
Horizontal drilling
(Andra, G. Armand)
20
EDZ permeability distribution
Structural and hydrogeological characterisation
of the excavation-disturbed zone in the Opalinus
Clay (Mont Terri Project, Switzerland) Paul
Bossart, Thomas Trick, Peter M. Meier,
Juan-Carlos Mayor Applied Clay Science 26 (2004)
429 448
Changes of permeability 2 order of magnitude
21
Research structure

1. Damage zone observations
2. Damage zone simulations
3. Evidences of permeability evolution in DZ
4. Constitutive equations for permeability evolution
5. Anisotropy considerations
6. Numerical simulations of coupled HM problems with
   permeability evolution

22
Conclusions

• Permeability may be strongly modified in EDZ in
  situ evidences.
• Some models relating permeability to strain or
  damage exist or are in development.
• Numerical modelling is complex but possible. Few
  simulations have been done.

23
Conclusions Open questions

• Lab evaluation of permeability evolution with
  strain / damage remains difficult. Nevertheless
  progresses are ongoing.
• Strain and micro fissure localisation effect on
  permeability needs to be better understood.
• Strong need of model validation both on lab and
  in situ experiments.

24
Collaborations

• Euridice
• SCK CEN
• ONDRAF
• ANDRA
• NAGRA
• University Barcelona, Lausanne, Paris,
  Grenoble, Lille, etc

25
European projects

• CATSIUS CLAY (benchmarks clay modelling)
• TIMODAZ (thermal effects and Excavated Damage
  Zone)
• FORGE (gas transfers)

26
Future cooperation with SCK-CEN

• FORGE project numerical simulation of gas flow
  Mol in situ test
• Gas flow in EDZ
• Anisotropy and elastoplastic behaviour
• Mol geological history and fracture prediction
• Doctoral thesis ?