Modelling the excavation damaged zone in Callovo-Oxfordian ... · B. Pardoen - S. Levasseur - F....

15
B. Pardoen - S. Levasseur - F. Collin - D. Seyedi Clay conference 2015 Brussels, Belgium Modelling the excavation damaged zone in Callovo-Oxfordian claystone using shear strain localisation

Transcript of Modelling the excavation damaged zone in Callovo-Oxfordian ... · B. Pardoen - S. Levasseur - F....

Page 1: Modelling the excavation damaged zone in Callovo-Oxfordian ... · B. Pardoen - S. Levasseur - F. Collin - D. Seyedi Clay conference 2015 – Brussels, Belgium Modelling the excavation

B. Pardoen - S. Levasseur - F. Collin - D. Seyedi

Clay conference 2015 – Brussels, Belgium

Modelling the excavation damaged zone in Callovo-Oxfordian

claystone using shear strain localisation

Page 2: Modelling the excavation damaged zone in Callovo-Oxfordian ... · B. Pardoen - S. Levasseur - F. Collin - D. Seyedi Clay conference 2015 – Brussels, Belgium Modelling the excavation

In situ evidences (Andra) : Anisotropy: - stress : σH>σh~σv Galery // to σh

- material : cross-anisotropy

Galery // to σH Major issues : prediction of the extension, fracturing structure and properties modifications.

Study : - fractures modelling with shear strain localisation,

- influence of permeability variation

Excavation damaged zone

EDZ Constitutive models Fractures modelling Permeability evolution Conclusions 2

(Armand et al. 2014)

Page 3: Modelling the excavation damaged zone in Callovo-Oxfordian ... · B. Pardoen - S. Levasseur - F. Collin - D. Seyedi Clay conference 2015 – Brussels, Belgium Modelling the excavation

Outline

EDZ Constitutive models Fractures modelling Permeability evolution Conclusions 3

1. CONSTITUTIVE MODELS

2. FRACTURES MODELLING

- GALLERY // TO σh

- GALLERY // TO σH

3. PERMEABILITY EVOLUTION

Page 4: Modelling the excavation damaged zone in Callovo-Oxfordian ... · B. Pardoen - S. Levasseur - F. Collin - D. Seyedi Clay conference 2015 – Brussels, Belgium Modelling the excavation

1. Constitutive models

EDZ Constitutive models Fractures modelling Permeability evolution Conclusions 4

1.1 Strain localisation with regularization - Coupled 2d gradient model : (Chambon et al., 1998 and 2001)

The continuum is enriched with microstructure effects. The kinematics include the classical one

(macro) and the microkinematics (Toupin 1962, Mindlin 1964, Germain 1973).

Biphasic porous media : solid + fluid (Collin et al., 2006)

Balance equations for

biphasic porous media : Bishop’s effective stress : Double stress :

ij ij ij rw wb S p

*

* 2

*

*

* * *

* *

,

q

i i

ij ijk i i i i i i

j j

w w

k

w

i w w

i

u ud G u d t u T D

p

u dx x

Mp m d Q p d q p d

t

x

x

2 *

ijk , i

j k

uf B

x x

Page 5: Modelling the excavation damaged zone in Callovo-Oxfordian ... · B. Pardoen - S. Levasseur - F. Collin - D. Seyedi Clay conference 2015 – Brussels, Belgium Modelling the excavation

1.2 Mechanical model :

Linear elasticity : Cross-anisotropic (5 param.) + Biot’s coefficient

Plasticity :

Van Eeckelen yield surface Cohesion anisotropy :

Hardening/softening of φ/c :

1. Constitutive models

/ / / / / /

/ / / /

/ / / / / /

/ / / /

// //

/ / / /

/ / / /

/ /

//

//

1- -

1- -

1- -

1

1

2

1

2

eijkl

E E E

E E E

E E E

E

G

G

D

ˆ 'tan C

cF II m I

30

'e e

ij ijkl kld D d / / / / / / // //, , , ,E E G

' ' '

' '

( ) ( ) ...ij i j

i i ii

ij ij

c a l l c A l b A l

l

2 2 2 2

11 3 1 11 3

2 2 2

1 2 3

1 1 3 1 3

3

e

ijkk

ij ij

s

Cb

K

/ /

/ /ij

b

b b

b

EDZ Constitutive models Fractures modelling Permeability evolution Conclusions 5

Page 6: Modelling the excavation damaged zone in Callovo-Oxfordian ... · B. Pardoen - S. Levasseur - F. Collin - D. Seyedi Clay conference 2015 – Brussels, Belgium Modelling the excavation

1. Constitutive models

EDZ Constitutive models Fractures modelling Permeability evolution Conclusions 6

1.3 Flow model : Advection of liquid phase (Darcy’s flow) : Water retention and permeability curves (Van Genuchten’s model) :

,

,

ij r w ww i w

w j

k k pm

x

, max 1

mn

cr w res res

r

pS S S S

P

2

1/

, , ,1 1m

m

r w r w r wk S S

1E-25

1E-24

1E-23

1E-22

1E-21

1E-20

1E-19

0 0.2 0.4 0.6 0.8 1

Srw (-)

Kw

(m

²)

Pham 2006

Semete 2008

Boulin 2008

Hoxha 2005

Homand 2004

van Genuchten0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1 10 100 1000

Succion (MPa)

Srw

(-)

LML - GL Gaz

Laego - GL Gaz

Yang 2008

Pham 2006

Boulin 2008

Zhang 2007

Hoxha 2004

van Genuchten - PGZ

Page 7: Modelling the excavation damaged zone in Callovo-Oxfordian ... · B. Pardoen - S. Levasseur - F. Collin - D. Seyedi Clay conference 2015 – Brussels, Belgium Modelling the excavation

2.1 Gallery // to σh : Anisotropic stress state, isotropic model Initial anisotropic stress state(Andra URL) :

pw,0 = 4.5 [MPa]

σv,0 = σh,0 = 12 [MPa]

σH,0 = 1.3 σv,0 = 15.6 [MPa] HM modelling in 2D plane strain state (LAGAMINE-Ulg) Excavation :

2. Fractures modelling

EDZ Constitutive models Fractures modelling Permeability evolution Conclusions 7

,0

,0

(1 )

(1 )

r r

w w wp p

Page 8: Modelling the excavation damaged zone in Callovo-Oxfordian ... · B. Pardoen - S. Levasseur - F. Collin - D. Seyedi Clay conference 2015 – Brussels, Belgium Modelling the excavation

2. Fractures modelling

EDZ Constitutive models Fractures modelling Permeability evolution Conclusions 8

Total

deviatoric

strain

σ/σ0=0.4 σ/σ0=0.2 σ/σ0=0.0

σ/σ0 = 0.40 σ/σ0 = 0.20 σ/σ0 = 0.00

End of

excavation

Plasticity

2ˆ ˆ

3eq ij ij

0 0.184

Page 9: Modelling the excavation damaged zone in Callovo-Oxfordian ... · B. Pardoen - S. Levasseur - F. Collin - D. Seyedi Clay conference 2015 – Brussels, Belgium Modelling the excavation

Fractures Total deviatoric strain Convergence

σ anisotropy is the predominant factor leading to strain

localisation and to the elliptical shape of the damaged zone.

2. Fractures modelling

0 0.184

0.5 m

4.6 m

EDZ Constitutive models Fractures modelling Permeability evolution Conclusions 9

Page 10: Modelling the excavation damaged zone in Callovo-Oxfordian ... · B. Pardoen - S. Levasseur - F. Collin - D. Seyedi Clay conference 2015 – Brussels, Belgium Modelling the excavation

2.2 Gallery // to σH :

Isotropic stress state (σ=12 MPa),

anisotropic model HM modelling in 2D plane

strain state

2. Fractures modelling

EDZ Constitutive models Fractures modelling Permeability evolution Conclusions 10

End of excavation

Page 11: Modelling the excavation damaged zone in Callovo-Oxfordian ... · B. Pardoen - S. Levasseur - F. Collin - D. Seyedi Clay conference 2015 – Brussels, Belgium Modelling the excavation

Cohesion evolution :

Anisotropy:

Initially : isotropic σij

Excavation : σr ↓ and σort ↑

2. Fractures modelling

' ' '

' '( ) ( ) ... i i i

ij i j i

ij ij

c a l l c A l b A l l

2 2 22 2 2 2 1 2 3

11 2 1 11 21 1 3 1 3

/ .c c l 2 3 3 0 58

EDZ Constitutive models Fractures modelling Permeability evolution Conclusions 11

Page 12: Modelling the excavation damaged zone in Callovo-Oxfordian ... · B. Pardoen - S. Levasseur - F. Collin - D. Seyedi Clay conference 2015 – Brussels, Belgium Modelling the excavation

Anisotropic stress state, anisotropic model σH,0 = 1.3 σv,0 > σv,0 = σh,0 = 12 [MPa]

Fractures Total deviatoric strain Convergence

Isotropic stress state in the gallery section does not lead to shear

strain localisation unless the material anisotropy is considered.

Material anisotropy seems to be the predominant factor leading

to strain localisation and to the elliptical shape of the damaged zone.

2. Fractures modelling

0 0.05

EDZ Constitutive models Fractures modelling Permeability evolution Conclusions 12

3.2 m

4 m

Page 13: Modelling the excavation damaged zone in Callovo-Oxfordian ... · B. Pardoen - S. Levasseur - F. Collin - D. Seyedi Clay conference 2015 – Brussels, Belgium Modelling the excavation

3.1 In situ evidences : Hydraulic properties are not homogeneous in the damaged zone. Influence of rock fracturing on intrinsic permeability. In situ permeability in Callovo-Oxfordian claystone (Armand et al. 2014, Cruchaudet et al. 2010b)

3.2 Permeability variation : Total deviatoric strain (if εeq > εeq

min ) End of Vertical Horizontal excavation y-axis x-axis α = 2 x 108 , β = 3

3. Permeability evolution

min

,0

1 ( )

2ˆ ˆ

3

ij

eq eq

ij

eq ij ij

k

k

EDZ Constitutive models Fractures modelling Permeability evolution Conclusions 13

Page 14: Modelling the excavation damaged zone in Callovo-Oxfordian ... · B. Pardoen - S. Levasseur - F. Collin - D. Seyedi Clay conference 2015 – Brussels, Belgium Modelling the excavation

3.3 Rock-atmosphere interaction (gallery air ventilation) : Water phases equilibrium at gallery wall, Kelvin's law : Air RH = 80%, pw = -30.7 [MPa] End of calculation Vertical y-axis Vertical y-axis

k(εeq) k(εeq) k = cst

3. Permeability evolution

,0

v c v

v w

p p MRH exp

p RT

EDZ Constitutive models Fractures modelling Permeability evolution Conclusions 14

Page 15: Modelling the excavation damaged zone in Callovo-Oxfordian ... · B. Pardoen - S. Levasseur - F. Collin - D. Seyedi Clay conference 2015 – Brussels, Belgium Modelling the excavation

Damaged zone strain localisation zone similar to in situ measurements modelling provide information about the rock structure and evolution within this

zone, as observed in situ.

rock anisotropy and properties modification

Conclusions

EDZ Constitutive models Fractures modelling Permeability evolution Conclusions 15