10 Current status of research in the Joint Project WEIMOS

Current Status of Research in the Joint Project WEIMOS
Andreas Hampel (Consultant), Till Popp (IfG), Kai Herchen (TUC)
8th US/German Workshop on
Salt Repository Research,
Design, and Operation
Middelburg, The Netherlands
September 5-7, 2017
WEIMOS:
Verbundprojekt: Weiterentwicklung und Qualifikation der gebirgsmechanischen Modellierung für die HAW-Endlagerung im Steinsalz
Joint Project: Further Development and Qualification of the Rock Mechanical Modeling for the Final HLW Disposal in Rock Salt
Institut für Gebirgsmechanik
GmbH Leipzig
Dr. Andreas Hampel
Wissenschaftlicher Berater / Scientific Consultant

8th US/German Workshop on Salt Repository
Research, Design, and Operation
Dr. Andreas Hampel
GmbH 2
WEIMOS
Joint Project WEIMOS
Partners
Germany:
Dr. Andreas Hampel, Mainz (Coordinator)
Institut für Gebirgsmechanik GmbH (IfG), Leipzig
Leibniz Universität Hannover (LUH)
Technische Universität Braunschweig (TUBS)
Technische Universität Clausthal (TUC)
United States:
Sandia National Laboratories, Albuquerque & Carlsbad
(associated partner, i.e. not funded by BMWi)

Dr. Andreas Hampel
GmbH 3
WEIMOS
Joint Project Period Objective Subjects: Modeling of ...
I 2004-2006
Studies and comparisons
of constitutive models and
calculation procedures
for the thermomechanical
behavior of rock salt
basic deformation
phenomena (creep, damage,
dilatancy, failure, ...)
II 2007-2010
3-D deformation, temporal
extrapolation, permeability
III 2010-2016
temperature influence,
damage reduction & healing
WEIMOS 2016 – 2019
Further development and qualification of the rock
mechanical modeling for the final HLW disposal in rock salt
Joint Project Series
Aim: Improved analysis and proof of the long-term integrity of the geological barrier rock salt
around an underground repository for all types of radioactive waste (incl. HLW)

Dr. Andreas Hampel
GmbH 4
WEIMOS
WP 1: Deformation behavior at small deviatoric stresses
WP 2: Influence of temperature and stress state on
damage reduction
WP 3: Deformation behavior resulting from tensile stresses
WP 4: Influence of inhomogeneities (layer boundaries,
interfaces) on deformation
WP 5: Virtual demonstrator
WP 6: Administrative work
damage reduction
Till Popp (IfG)
Kai Herchen (TUC)
Till Popp (IfG)
Andreas Hampel
presented by
Andreas Hampel
Work Packages

Dr. Andreas Hampel
GmbH 5
WEIMOS
WEIMOS WP 4: Influence of inhomogeneities (layer boundaries, interfaces)
Munson et al. (1990):
Sandia Report SAND89-2671
Important questions:
• Influence on convergence?
(e.g. sliding on clay seams at WIPP)
• Influence on damage and dilatancy in the DRZ?
• Modeling of these phenomena?
Experimental investigations
 RESPEC lab: shear tests on layered rock salt specimens
 Proposals of Sandia (1983, 2016): In-situ experiments
Objective:
 Study, develop further and improve the modeling
=> Reduce uncertainties of simulation results,
increase confidence in the results
Stratigraphy at WIPP
current status:
upcoming drilling of layered salt cores at Intrepid mine near WIPP:
rock salt with clay seams, salt/anhydrite, salt/polyhalite interfaces

Dr. Andreas Hampel
GmbH 6
WEIMOS
WEIMOS WP 5: Virtual demonstrator
Objective: Simulation of a complex model to demonstrate the improved modeling of the various
investigated phenomena:
 small deviatoric stresses
 damage reduction and healing
 influence of interfaces/layer boundaries
 influence of e.g. thermally induced
tensile stresses
Simulations: step 1: open drift
step 2: installation of the dam
step 3: post-operational phase & long-term behavior
rock salt

Dr. Andreas Hampel
GmbH 7
WEIMOS
rock salt
WEIMOS WP 5: Virtual demonstrator
current status:
extrude the plane strain model of Room D from Joint Project III to 3-D,
add one or two clay seams,
perform test simulations (find appropriate discretization, ...)
Joint Project III:
2-D vertical cut
at Room D
Virtual Demonstrator
clean salt
argil. salt
anhydrite
polyhalite
WEIMOS:
preliminary VD model

Dr. Andreas Hampel
GmbH 8
WEIMOS
Work Packages
damage reduction
Till Popp (IfG)
Kai Herchen (TUC)
Andreas Hampel
presented by
Andreas Hampel
Till Popp (IfG)

Dr. Andreas Hampel
GmbH 9
WEIMOS
WP 1: Deformation behavior at small deviatoric stresses Motivation
The challenge …,
how does salt deform in the long term?
Boundary conditions:
Fore cast period: 103 < time (years) < 106
Deformations: 0.1 < e < 1
Temperatures: 20°C - 200°C
Def. Rates: 1∙10-17 < e (1/s) < 3∙10-11
Creep mechanisms:
Pressure solution creep vs. dislocation creep
 Test duration is usually limited!
modified after Urai, 2012
Deformation-mechanism map
0.1
Dislocation creep
Pressure
Solution
Creep
In situ
lab
n = 1
n = 5

Dr. Andreas Hampel
GmbH 10
WEIMOS
WP 1: Deformation behavior at small deviatoric stresses Comparison of different investigations
BGR (2016): Type ERAM salt, Ø=100 mm L = 200 m, t < 1.4a
Berest et al. (2015): Salt mine Varangeville
- Type Avery Island salt, t < 1.5 a
Berest et al. (2017): Salt mine Altaussee
- Type: Avery Island, Hauterives, Gorleben t ≈ 2 a
Dead weight
setup
Sample size: Ø=70
mm L = 140 m
3D-simulation of salt dome uplift
"humid"
bedded
salt
"wet" salt
glacier
Residual stress?
"dry" salt
dome

Dr. Andreas Hampel
GmbH 11
WEIMOS
WP 1: Deformation behavior at small deviatoric stresses IfG – improved creep rigg
Axial Force: 200 kN
Sample size:
 = 60mm,
l = 120mm
Capacitive displacement
system
Quartz rod
CSH02FL-CRm1,4
Resolution 0.15 nm
Linearity 0,05 m
Temperature sensitivity -2.4 nm/°C
Measuring principle
The principle of capacitive displacement
measurement using the capaNCDT
(capacitive Non-Contact Displacement
Transducer) system is based on how an
ideal plate-type capacitor operates. The
two plate electrodes are represented by
the sensor and the opposing
measurement object

Dr. Andreas Hampel
GmbH 12
WEIMOS
1.0E-09
1.0E-08
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
0.1 1 10
CreepRate[1/d]
Difference Stress [MPa]
wipp clean salt T=27°C
T=30°C - GS
T=30°C - Mi
T=60°C - GS
T=60°C - Mi
T=80°C - GS
T=80°C - Mi
2016/17 T=25°C
2016/17 T=60°C
2016/17 T=80°C
2016/17 T=100°C
WP 1: Deformation behavior at small deviatoric stresses Lab program / current data base
IfG lab program
No. T
Duration
[d]
s1
[MPa]
s3 = p
[MPa]
Ds
[MPa]
TCC
24
25°C
60°C
10
50
80
80
80
20
28
26
26
26
20
22
0
8
6
4
4
TCC
21
25°C
60°C
10
50
80
80
80
20
26
24
24
24
20
22
0
6
4
2
2
TCC
22
25°C
60°C
10
50
80
80
80
20
24
22
22
22
20
21
0
4
2
1
1
TCC
23
80°C 10
50
80
80
80
20
28
26
26
26
20
22
20
0
8
6
4
6
TCC
27
80°C 10
50
80
80
80
20
26
24
24
24
20
22
20
0
6
4
2
4
TCC
29
80°C 10
50
80
80
80
20
24
22
22
22
20
21
0
4
2
1
1
TCC
28
25°C
25°C
40°C
60°C
80°C
100°C
10
50
50
50
50
50
20
24
24
24
24
24
20 0
4
4
4
4
4

Dr. Andreas Hampel
GmbH 13
WEIMOS
WP 1: Deformation behavior at small deviatoric stresses Modelling of Salt Dome Recent Uplift Rate
Example: Development of salt dom Gorleben-Rambow
Recent Uplift Rate
Target Value:
0.01….0.05 mm/a

Dr. Andreas Hampel
GmbH 14
WEIMOS
WP 1: Deformation behavior at small deviatoric stresses The generic model – current situation
12 km
Triassic/ Jurassic r= 2,45 g/cm³
Cretaceous
r = 1,8 g/cm³
r = 2,32 g/cm³
Upper Permian
(Rock Salt )
r = 2,17 g/cm³
Tertiary, Quaternary
3,5km
r = 2,33 g/cm³
Lower Permian

Dr. Andreas Hampel
GmbH 15
WEIMOS
WP 1: Deformation behavior at small deviatoric stresses Outcome with the BGRa - approach
Vertical Velocity - after 1 Mio years
Z-vel
in m/day
5E-10 m/d = 1.8E-4 mm/yrs
v. Mises Stress
seff<1MPA
8E-5 mm/yrs
Recent Uplift Rate
Target Value:
0.01….0.05 mm/a

Dr. Andreas Hampel
GmbH 16
WEIMOS
WP 1: Deformation behavior at small deviatoric stresses Outcome with the IfG-GS Model
Vertical Velocity - after 1 Mio years
Z-vel
in m/day
9E-8 m/d = 0.032 mm/yrs
0.03 mm/yrs
v. Mises Stress
seff<1MPA
approx. 3 orders of magnitude
Recent Uplift Rate
Target Value:
0.01….0.05 mm/a

Dr. Andreas Hampel
GmbH 17
WEIMOS
WP 3: Deformation behavior resulting from tensile stresses The problem
• Tensile strength and tensile damage
processes play dominant roles for
development of micro-cracks and
progressive damage, usually described by
the term “Excavated Damage Zone” (EDZ).
• Tensile stresses may be generated by
thermal effects during heating or cooling.
Asse
WIPP

Dr. Andreas Hampel
GmbH 18
WEIMOS
WP 3: Deformation behavior resulting from tensile stresses The approach
• Tensile strength and tensile damage
processes play dominant roles for
development of micro-cracks and
progressive damage, usually described by
the term “Excavated Damage Zone” (EDZ).
• Tensile stresses may be generated by
thermal effects during heating or cooling.
WEIMOS-Approach:
 Comparison, how tensile stresses are treated in
the various material laws
 Benchmark calculations of lab tests and field
constellations
 Evaluation of the relevancy of tensile stresses Damage development for a drift
at the WIPP-site
(Günther et al., 2015)

Dr. Andreas Hampel
GmbH 19
WEIMOS
WP 3: Deformation behavior resulting from tensile stresses Recalculation Brazilian Test
Lab test
Loading Rate Labor :
𝑣 =
1𝑚𝑚
100𝑠
Numerical simulation
Günther/Salzer Approach

Dr. Andreas Hampel
GmbH 20
WEIMOS
Work Packages
damage reduction
Till Popp (IfG)
Kai Herchen (TUC)
Andreas Hampel
presented by
Andreas Hampel
Till Popp (IfG)

Dr. Andreas Hampel
GmbH 21
WEIMOS
WP 2: Influence of temperature and stress state on damage reduction
Development of micro-cracks and progressive
damage at the opening contour (EDZ) after
excavation because of rock stress rearrange-
ments and the exceeding of the structural
strength boundary
Reduction of load bearing capacity and the
development of drift and shaft parallel by-
paths and secondary permeability
Knowledge of the damage reduction process
is important for the repository safety case
Motivation
leads to
therefore
Wall of an open driftSealing system / dam
Sketch of a repository
Shaft
Dam

Dr. Andreas Hampel
GmbH 22
WEIMOS
WP 2: Influence of temperature and stress state on damage reduction
Basic assumptions for the damage reduction process:
 Long-term change in stress conditions in the near field of sealing
structures as a result of convergence process
 Creeping of the rock salt mass on the sealing structure (hard
inclusion) / on the backfill material (soft inclusion) with increasing
contact pressure
 Reduction of the damage and permeability development as a
result of crack closure and healing effects
WEIMOS-Approach:
Healing tests with different stress
states and temperatures
Qualification and improvement of
material models based on lab tests
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Simulation of a complex
model to demonstrate the
improved modeling
Approach
Stiff sealing
system
EDZ
Contact
pressure
Convergence
pressure
Gas- and liquid
tight rock salt mass

Dr. Andreas Hampel
GmbH 23
WEIMOS
WP 2: Influence of temperature and stress state on damage reduction TUC laboratory tests
4 Test machines
Sample size: 300/150 mm
V
EMC-System
30 MPa
2 MPa
29 MPa
1MPa/min

Dr. Andreas Hampel
GmbH 24
WEIMOS
WP 2: Influence of temperature and stress state on damage reduction TUC lab test results
1. Series
Temperature = 35°C Salt type: Asse
1st Test machine
Steel-dummy
Measurement of oil- and
test plant compressibility
Stopped for dilatancy
measurement with
immersion weighing
2nd Test machine
Salt sample
„Ass471“
4th Test machine
Salt sample
„Ass466“
3rd Test machine
Salt sample
„Ass470“
Stopped for dilatancy
measurement with
immersion weighing

Dr. Andreas Hampel
GmbH 25
WEIMOS
WP 2: Influence of temperature and stress state on damage reduction TUC lab test results
& further tests
3. Series2. Series
Stress(MPa)
Stress(MPa)
1. Series
Temperature = 35°C
Temperature = 60°C Temperature = 35°C
Axialstresssigz
Confining
stress sigx,y
Axialstresssigz
Confining
stress sigx,y

Dr. Andreas Hampel
GmbH 26
WEIMOS
WP 2: Influence of temperature and stress state on damage reduction Modified TUC healing test
Axialstrain(%)
Test characteristic
1
1
2
2
3
3 Loading path
Dilatancy strength
sDiff = 28 MPa
sDiff = 28 MPa
Damage free
creep
Healing
Loading history
Damage induced
creep
Temperature = 35°C
Dilatancy(%)
Ultrasonicwavevelocity(-)

Dr. Andreas Hampel
GmbH 27
WEIMOS
damage reduction
Till Popp (IfG)
Kai Herchen (TUC)
Till Popp (IfG)
Andreas Hampel
presented by
Andreas Hampel
Work Packages

10 Current status of research in the Joint Project WEIMOS

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10 Current status of research in the Joint Project WEIMOS