Rock mechanics of the Callovo-Oxfordian claystone at ... - EGT...packages & general service HL LLW disposal zone Shafts for construction and ventilation DRD/MFS/14-0038 Underground

AGENCE NATIONALE POUR LA GESTION DES DÉCHETS RADIOACTIFS© Andra

G. Armand, A. Noiret, J. Zghondi, R. de La Vaissière, N. Conil, J. Morel, F. Bumbieler

Rock mechanics of the Callovo-Oxfordianclaystone at the Meuse/Haute-Marne

Underground Research Laboratory and consequences for CIGEO repository design

DRD/MFS/14-0038

Symposium « Rock Mechanics and Rock Engineering of Geological Repositories in Opalinus

Clay and Silmilar Claystone »

AGENCE NATIONALE POUR LA GESTION DES DÉCHETS RADIOACTIFS© Andra© Andra

Legal Framework in France

The 1991 Waste Act

Creation of « Andra » as a public independent body

3 research areas for High Level Long-lived Waste: partitioning/transmutation; long term storage; geologic disposal

2005: Feasibility assessment of safe geological disposal in Callovo-Oxfordian claystone layer (Meuse/Haute-Marne URL)

The 2006 Programme Act: Reduce/avoid the burden on future generations

Reduce volume and harmfulness of wastes

SF reprocessing + waste treatment and conditioning

Reference option for final waste that can no longer be treated: geological repository with respect to reversibility (100 y at least)

Application: 2015; Operation: 2025

Continue research on interim storage (Andra) and partitioning/transmutation (CEA) and on a complementary basis.

Cigéo Project

DRD/MFS/14-0038


Architecture of CIGEO Project

Excavation ActivitiesNuclear

Activities

Surface facilities will be split in 2 parts

Ramps for waste packages &

general service

HL LLW disposal zone

Shafts for construction

and ventilation

DRD/MFS/14-0038

Underground facility : cells will be added progressively as the operation progresses until they reacha total maximum area of about 15 km2, after about 100 years

CIGEO: Industrial Center for Geological Disposal


Zoom on the IL-LLW disposal cell

Length: 400 m

Excavated diameter: 9-11 m

2x2 or 3x3 packages

No. of containers: 800-1,900

DRD/MFS/14-0038


Zoom on the HLW disposal cell

Length 80 m

Diameter: 70 cm

No.of containers: 7-20

(for 40 m)

Package of vitrified waste (CID-V)

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Needs in geomechanic

Specific feature of such projectUnderground nuclear facility

Long operational life time

Size (length of drift,…)

DRD/MFS/14-0038

Need a good understanding of rock and structure interaction The Callovo Oxfordien THM behaviorThe structure behavior (concrete,…)It is necessary to take into account the consequences of the construction method (velocity of digging, time between digging and installation, type of material as structure

Design of different elements of the repository

Input for the performance assessment calculation


Geomechanical research at the URL

The performance/safety assessment and technology demonstrationare the main objectives of research programs. In geomechanic:

To study hydro mechanical behavior of claystone during drift and shaft excavation (short and long term behavior)

Impact of digging and support method Orientation of drift

To characterize the Excavation Damaged Zone (EDZ)To characterize the Thermo Hydro Mechanical behaviorTo perform sealing experimentsTo study the impact of gas transfert in the rock/EDZ/seals

EDZ characterization for safety assessment calculation

HM behavior to design support of the repository drifts

DRD/MFS/14-0038

In situ experiment serve for demonstration issueIn situ measurements are compared with numerical modeling and useful to validate and develop HM model


The Callovo Oxfordian claystone

DRD/MFS/14-0038


Paris

URL

226 km

The Callovo-Oxfordian argillite at the MHM site (Bure)

• Age: 155 million year• Depth at the site: ~500 m• Thickness at the site: ~130 m

• Mineralogy: ~ 45% clay + carbonates and silicates

• low water content• No free water, no water flow• Diffusive transfer only• Retention capacity

DRD/MFS/14-0038


Axial displacement

Dev

iato

ricst

ress

(1-

3)

Elasticity

Damage

Failure

Hoxha,2004

Rock properties of the COX

Callovo Oxfordian claystoneproperties at the 490 m level:

Mineralogy:50-55% clay minerals 20-25% carbonatearound 25% quartz silts

Very low permeability (5.10-20 m²)Short-term behavior, triaxial test: non linear and post-peak depending on 3

Long term behavior, uniaxial creep test:

Creep strain rate increases non-linearly with the applied deviatoric stressCreep rate (Andra 2005):

4.10-12 < creep rate <1.60.10-12

(test duration 1 to 3 years)

Long-term behavior according to the modified Lemaître’s model

DRD/MFS/14-0038

Rock parameter Ind. ValueBulk specific gravity 2.39 g/cm3

Porosity n 16 2%

Young modulus EE///E

4000 1470 MPa1.2 to 1.5

Poisson Ratio 0.29 0.05Uniaxial compressivestrength UCS 21 6.8 MPa

Hoek & Brown criteriaSm

c (MPa)

0.432.533.5

Intrinsic permeability k 5 10-20 m2

Water content w 7.2 1.4 %

Residual


HM behavior of drift (at the main level of the URL)

DRD/MFS/14-0038


Experimental strategy for the study of drift behaviour

1- Use the underground laboratory for observing real behavior of drift under natural conditions

Each drift excavation in the URL is a geomechanical experiment in itself

2- Sequencing of drift construction to highlight the role of support/excavation methods

Start with "soft" support drift to study the behavior of COX

Skip to rigid support emplaced after a delay of several months

Then emplace rigid support sooner after the excavation of the gallery

3- Using parallel drift to compare the different behavior

4- Use mine by experiment (borehole emplaced before the excavation) to study the HM behaviour (at short and long terms)

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Meuse/Haute-Marne underground research laboratory

DRD/MFS/14-0038

A huge program of experiments is planned to characterize the response of the rock to different drift construction methods

12 MPa

1,3 h

h

Anisotropic in situ stress field

• 1.3km of drifts• 573 boreholes• 7 300 m of cores• Data acquisition : 7 000

sensor measurements


Excavation methods

Test different excavations and supports in parallel drifts to better understand the behavior of the drift by comparison (from low support to stiff support like concrete segments)

DRD/MFS/14-0038

Road header

Pneumatic hammerRoad header under shield


Different drift supports (1/2)

DRD/MFS/14-0038

radial rockbolts (3 m long),18 cm of fiber reinforced shotcrete,12 yieldable concrete wedges (hiDcon®)

GCS drift

GCS drift + 27 cm of concretecasted in place 6.5 month afterexcavation

GCR driftradial rockbolts (3 m long),45 cm of fiber reinforced shotcreteemplaced in four layer

BPE drift


Different drift supports (2/2)

Segment emplacement methodSegment of 45 cm thickGap filling with radial injection of mortar

DRD/MFS/14-0038

Classical mortarCompressible mortar

with polystyrene ball


Mine by experiment

Experimental set up: “Mine by experiment” Boreholes (Displacement, pore pressure) emplaced before excavationConvergence measurements, geological survey, boreholes (displacement)Borehole to characterize EDZ (permeability measurements, velocity survey,

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Around GCSAround GCR


Some example of results on drifts:

Excavation induced fracture

HM behaviour of drift

DRD/MFS/14-0038


Geological survey

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Fracture supérieure du chevron -Shear

Fractures du bombement - extensionFracture inférieure du chevron - Shear

Ecaillage concave (Eco) - ShearFCh/ECo - Shear

Drift // H Drift // h

3D scan is performed to map the front face and analyze fracture orientation (GEOTER)

Fractures types are the same in the two directions but number location and extent differ


Induced fracture in drift parallel to H

Structural analysis in an area with numbers of borehole exhibits :

Complex pattern

Extent of shear fracture is larger than tensile fracture

Deep in the rock the shear fracture are visible on different borehole

DRD/MFS/14-0038


Induced fractures network

Type of fracture are similar but the extend depend of dirft orientation versus in situ stress state

DRD/MFS/14-0038

Drift Orientation

Extensional fractures extent

Shear fractures extent

Min. Average

Max. Min. Average

Max.

N65// h

Ceiling0.2×D

0.3×D

0.4×D 0.5×D 0.6×D0.8×D

Wall0.1×D

0.1×D

0.2×D - - -

Floor0.2×D

0.4×D

0.5×D 0.8×D0.8 ×D

1.1×D

N155// H

Ceiling-

0.1×D

0.15×D

- - -

Wall 0.01×D

0.2×D

0.4×D 0.7×D 0.8×D1.0×D

Floor-

0.1×D

0.15×D

- - -

G. Armand, F. Leveau, C. Nussbaum, R. de La Vaissiere, A. Noiret, D. Jaeggi, P. Landrein, C. Righini, 2014, Geometry and Properties of the Excavation-Induced Fractures at the Meuse/Haute-Marne URL Drifts, Rock mechanic and Rock engineering, Volume 47, Issue 1, pp 21-41


Convergence for drift //

DRD/MFS/14-0038

Drift GCS (// to to H)

Horizontal convergence is higher the vertical one (ratio of 2,1)Velocity decrease as a function of timeNo significant difference between excavated with pneumatic hammer and road header

Deformation rates


Convergence for drift // h

Drift GED // to to h

DRD/MFS/14-0038

• Horizontal convergence is higher the vertical one (ratio of Cv/Ch = 4 to 5 )

• Velocity decrease as a function of time• After 1 year , rates <10-10 s-1 Deformation rates

Convergence depends of the drift orientationHighest convergence is observed where the extend of induced fractures is larger


Location of the boreholes network

DRD/MFS/14-0038

5

0

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25

30

35

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45

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55

0 5 10 15 20 25 30 35 40 45 50 55 60 65

ylocal[m]

x local [m]

15

10

5

0

5

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5 0 5 10 15 20 25 30 35 40 45 50 55

zlocal[m]

y local [m]

OHZ1111 OHZ1122 OHZ1123 OHZ1501 OHZ1502OHZ1511 OHZ1512 OHZ1521 OHZ1522 OHZ1523OHZ1524 OHZ1525 OHZ1526 OHZ1701 OHZ1702OHZ1703 OHZ1704 OHZ1705 OHZ1707

19 boreholes (mine by test et SMR)

• 8 extensometers

• 3 inclinometers

• 8 multipacker systems


Steps of excavation are visible:

2 spans ahead the front, around 2.4 m7 spans beyond the front face, around 8.4 m. At this distance, the long-term behavior is predominant on the instantaneous strain

DRD/MFS/14-0038

Horizontal radial displacement

Extensometer drilled horizontal from the GAT to the GCS and the last anchor (01) is nearly at the sidewall of the GCS

dis

pla

cem

ent

(mm

)


Horizontal radial displacement

Radial deformation measured in drift GCS has been reanalyzed in order to separate instantaneous and differed response to digging.

DRD/MFS/14-0038

Elastoplastic deformation represents 40%–45% of the total deformation at 90 days, and around 30% at 900 days. Farther 5.8 m deep in the rock, differed deformation is very small. The contribution of the far field is about 5% of the total elastoplasticdeformation, 4% of the differed deformation at 90 days and less than 1% at 900 days. the very small contribution of the far field to the total deformation at the

wall exhibits that the differed deformation comes from the near field


The distance of influence of the excavation is estimated at 20 m

Overpressure of several MPa (3 MPa in chambers 4 at 4.8 m from the GCS wall)

Drop of pressure at the front crossing

DRD/MFS/14-0038

Pore pressure response (horizontal)

Multipacker system located oblique horizontal from the GAT to the GCS

0

10

20

30

40

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60

70

80

01/04/10

01/05/10

31/05/10

30/06/10

30/07/10

29/08/10

28/09/10

28/10/10

27/11/10

porepressure(bars)

OHZ1521_PRE_01at 37,9m(d= 2,4m/PM35,7)OHZ1521_PRE_02at 33,7m(d=1,1m/PM33,5)OHZ1521_PRE_03at 32,7m(d=1,9m/PM33,0)OHZ1521_PRE_04at 29,3m(d=4,8m/PM31,3)OHZ1521_PRE_05at 23,4m(d=9,9m/PM28,3)PM

First chamber was destroyed during GCS excavation

side view top view0

10

20

30

40

50

60

70

80

08/06/2010

15/06/2010

22/06/2010

29/06/2010

06/07/2010

13/07/2010

20/07/2010

27/07/2010

03/08/2010

10/08/2010

Pressio

n(bars)


Lower overpressures in the vertical direction (1order of magnitude difference with the horizontal plane)Drop of pressure is observed near the front face and stabilization as a function of the pore pressure gradientDespite the initial stress state is nearly isotropic around the GCS drift, the pore pressure response is anisotropic

DRD/MFS/14-0038

Pore pressure response (vertical)

Multipacker system located oblique and rising from the GAT to the GCS

0

10

20

30

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50

60

70

80

01/04/10

01/05/10

31/05/10

30/06/10

30/07/10

29/08/10

28/09/10

28/10/10

27/11/10

porepressure(bars)

OHZ1522_PRE_01at45,6m(d=6,9m/PM37,8)OHZ1522_PRE_02at41,6m(d=4,5m/PM35,8)OHZ1522_PRE_03at38,7m(d=3,5m/PM34,4)OHZ1522_PRE_04at35,7m(d=3,5m/PM32,9)OHZ1522_PRE_05at31,71m(d=4,9m/PM30,9)PM

side view top view0

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15/06/2010

22/06/2010

29/06/2010

06/07/2010

13/07/2010

20/07/2010

27/07/2010

03/08/2010

10/08/2010

17/08/2010

Pressio

n(bars)


HL-LL waste disposal cells

Micro tunnel of 70 cm in diameter

DRD/MFS/14-0038


Step by step approach with demonstration and scientific objectives

test the making up of the cell (head & usable part)Study the behaviour of the cell under isothermal conditiontest the making up of different equipments into the cell (base plate, shield steel plug and closing plate),verify the suitable working of the head insert to absorb the thermal dilation of the sleeve,provide data on the casing behaviour under thermal loading,verify the design of the cell head to limit thermal gradients on the drift wall,study the THM behaviour of the interface between rock and casing and of the surrounding rock.

CAC and TEC experiment :smaller scale experiment on steel casing in boreholes

DRD/MFS/14-0038

AGENCE NATIONALE POUR LA GESTION DES DÉCHETS RADIOACTIFS© Andra© AndraDRD/MFS/14-0038

Andra concept for HL-LL waste disposal cells

Horizontal micro tunnels, about 700 mm in diameter and 100m long, cased with steel sleeves

Usable part used for containers disposal,

Head part (“insert”) 10 m long used for cell sealing

End steel plug (base plate), shield steel plug and closing plate

Laser guided auger drilling machine

Casing pushed in place during drilling by 2 m long elements welded or socketed to each others

Retraction of the machine after excavation

Demonstration program in the URL to test the feasibility of construction and the behaviour of such disposal cells


ALC experiment

)) Phase 1 (2009): cell of 20 m length

)) Phase 1 bis (2010): cell of 40 m length

)) Phase 2 (2011): cell of 40 m length withsensors on the sleeve

Insert of 7 m to test emplacement of thehead

)) Phase3.1 (2012): cell of 100 m length

DRD/MFS/14-0038


HLW disposal cells

)) Phase 3.2 (2012/2013):

EDZ

Heating dummy packages empty insert

Closed fractures

Delayed phase: closure plugging

Initial phase: easily retrieviable package stage

• Full-sized reproduction of a HLW cell(WP3 of EC project LUCOEX) => THMbehavior

Main objectives :• Test the making up• Verify the design of the cell head to absorb

the thermal dilation of the casing and to limit thermal gradients on the drift wall.

DRD/MFS/14-0038


Excavation induced fractures around micro tunnel

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Similar shape of fracture pattern at different size (// H)

HA vault

Fractures model around driftRock bolt


HA cell // to H (CAC1601)

Relative humidity in the void Convergence of casing

60

65

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75

80

85

90

95

100

0 50 100 150 200 250 300 350

Humidité

Relativ

e(%

)

jours

HR à 35 mHR à 25 mHR à 15 mHR à 7 m

Objective (Phase 2)Behavior of the void : water arrival versus time dependant behaviour and closure of the void

Loading of the steel casing

Test of optical fibers method

HM behaviour of the micro tunnel

3

2

1

0

1

2

3

0 50 100 150 200 250 300 350

Convergence(m

m)

days

vertical / 35 m deephorizontal / 35 m deepvertical / 25 m deephorizontal / 25 m deepvertical / 15 m deephorizontal / 15 m deep

DRD/MFS/14-0038


P

v

h

t < 60 daysLoading localized in the horizontal direction

60 days < t < 160 daysanisotropic loading

h > v

t > 160 daysDecrease of anisotropic loading

v

h

75

15+

Expriment in borehole with steel casing (1/2)

o steel N80 ( y = 550 MPa)

o Borehole : Ø = 146 mm

o casing : Øout = 143 mm, thickness = 4,5 mm

DRD/MFS/14-0038


5 - 15°

CAC1001 : /e 32

CAC1002 : /e 32

CAC1003 : /e 47

Orthoradial deformation at 8 m deep in borehole

400

300

200

100

0

100

200

300

400

0 50 100 150 200

(MPa)

days

CAC1001 (e=4,5mm)CAC1002 (e=4,5mm)CAC1003 (e=3 mm)

y = 550 MPa

Expriment in borehole with steel casing (2/2)

DRD/MFS/14-0038

Remain in elastic domain, no problem of stability of the casingBut it will contribute to corrosion under stress which is a difficulty for the design of the casing


HL-LL waste disposal cells

The experiment performed at the URL serve to optimize the concept

In 2009 the reference length in the concept was 40 m and all cell are parallel to H

It was demonstrate that a longer depth could be reached= now reference length = 80 m

It was confirmed that excavation of cell along H is better than h

Elastic deformation in traction have been observed (due to the difference of convergence rate in horizontal and vertical direction) and will contribute to corrosion under stress

Backfill the void in between the casing and rock (concrete with bentonite)A test has been performed in November 2013

DRD/MFS/14-0038


Summary (1/2)

Experiments in the MHM URL serve to Demonstrate feasibility of a deep geological repository and upscale data obtained on sample (diffusion/retention, permeability,…) Demonstrate the working of the different conceptOptimize the different conceptsData based to develop/validate model

But you also needFundamental research to assess the physical process in order to develop model to extrapolate data to the lifetime of a repository

Safety calculation to always check if optimization do not decrease the safety At the beginning of the repository construction, final design will be tested in the repository to check in the repository conditions if predicted behavior is observed.

DRD/MFS/14-0038


Summary (2/2)

Behavior of the driftTwo major phenomena can be distinguished :

Elastoplastic and damage mechanisms seems to be predominant at short termsDrift ‘s deformations develop as a function of time

During excavation work, fractures network are induced (mainly shear fracture 75%, extensional fracture 25%)The extend of the fracture network depend on the drift orientation versus the in situ stress field and could not be explain by the anisotropy of the stress field

No impact of the method of excavation (BRH versus MAP)Shear fractures (deep in the rock) exhibit low transmissivityWith water uptake, fractures transmissivity decreases drastically

Anisotropic convergence of the drift are observed :anisotropy of convergence develops in two opposite directions in drifts parallel and perpendicular to H major convergence is measured where the fracture zone is located

Differed deformations After one year, deformation rates are in the same velocity range than the one measured on creep test or lower.Most of the differed deformation appears in the fractured zone

DRD/MFS/14-0038


Thank you for your attention

Danke Ihnen für Ihre Aufmerksamkeit

Merci pour votre attention

DRD/MFS/14-0038

G. Armand, F. Leveau, C. Nussbaum, R. de La Vaissiere, A. Noiret, D. Jaeggi, P. Landrein, C. Righini, 2014, Geometry and Properties of the Excavation-Induced Fractures at the Meuse/Haute-Marne URL Drifts, Rock mechanic and Rock engineering, Volume 47, Issue 1, pp 21-41

G. Armand, A. Noiret, J. Zghondi, D.M. Seyedi,2013, Short- and long-term behaviors of drifts in the Callovo-Oxfordian claystone at the Meuse/Haute-Marne Underground Research Laboratory, Journal of Rock Mechanics and Geotechnical Engineering 5,pp 221–230

Documents

Rock mechanics of the Callovo-Oxfordian claystone at ... - EGT...packages & general service HL LLW disposal zone Shafts for construction and ventilation DRD/MFS/14-0038 Underground