rock mechanics/geophysics larry costin, sandia national labs paul young, university of toronto...
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![Page 1: Rock Mechanics/Geophysics Larry Costin, Sandia National Labs Paul Young, University of Toronto Discussion Points November 12, 2004 DUSEL Workshop](https://reader030.vdocument.in/reader030/viewer/2022032414/56649ef35503460f94c060c6/html5/thumbnails/1.jpg)
Rock Mechanics/Geophysics
Larry Costin, Sandia National LabsPaul Young, University of Toronto
Discussion Points
November 12, 2004
DUSEL Workshop
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Path Forward
• Identify the “big questions” that can be addressed by DUSEL in a unique way
• Develop a “roadmap” for evolution of experiments & facilities
• Define infrastructure requirements• Integrate with other groups to identify experiment
sets with compatible infrastructure requirements• Identify significant education outreach
opportunities
We are here
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Motivation• Significant trend toward greater utilization of underground space
– Critical infrastructure– High hazard facilities– Environmental protection– Urban development
• Current engineering practice has heavy reliance on empirical design rules– Influence of discontinuities– Environmental factors– Time-dependent behavior– Lack of characterization methods for spatial variability
• Few opportunities for long-term R&D efforts
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The Big Questions?• Long-term degradation processes – physical, chemical, coupled –
leading to weakening, rock fall, collapse over many years.• Effect of spatial variability of rock mass properties on in situ
stresses and stability of openings. • Characterizing spatial variability. Validation of methods.• Measurement of in situ stresses.• TMHC(B) coupled processes and model validation.• Validation of mechanics concepts – DEM methods.• Geophysical imaging and/or characterization of discontinuities
and other features affecting rock mass behavior. • Data fusion – can we improve detection and characterization with
data from multiple sensor types?
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Unique Opportunities?
• Ability to mine through – ground truth validation of measurement and characterization methods.
• Long-term access for science. Ability to make measurements/observations over many years.
• Deep earth geophysics observatory. • International collaboration.
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URL Experience
• Excavation scale testing for numerical model validation – Mine-by Experiment
• Tunnel Sealing eXperiments to simulate radioactive waste repository conditions –TSX
• Seismic methods used for remote detection and quantification of damage
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Monitoring and Modelling Results: URL Mine-by
Moment magnitude
PFC synthetic seismicity
0
48 days
Potyondy and
Cundall, 2001
-2.2
-3.7
Recorded seismicity
PFC simulationExcavatio
n damage
Hazzard et al, 2000
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URL Tunnel Sealing Experiment (TSX)• Phases: Excavation (1997/98); Pressurisation (1999/02); Heating (2003);
Cooling and Depressurisation (2004).• Scale: Seal 20m x 4.4m x 3.5m
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URL TSX Induced Seismicity (1997 – 2003) – Response to Excavation, Pressurization, and Heating
• High rate of MS activity during excavation.
• Decay of MS events with pressurisation.
• Increase around chamber again, especially in the roof, during heating.
A : Tunnel Excavation
B : Bulkhead Key Excavation
C : Bulkhead Seal Construction
D : Chamber Fill and Pressurization to 2MPa
E : Chamber Pressurization to 4MPa
F : Chamber Heating to 80°C
0
1
2
3
01
/02
/97
20
/08
/97
08
/03
/98
24
/09
/98
12
/04
/99
29
/10
/99
16
/05
/00
02
/12
/00
20
/06
/01
06
/01
/02
25
/07
/02
10
/02
/03
29
/08
/03
Dis
tan
ce
to
Ch
am
be
r W
all
(m)
A B C D E F
• 95% of the events occur within 1.4m of the chamber wall.
• Events during heating do not extend further than during excavation
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URL TSX Seismic Velocity Measurements 1997-2003: Temporal Changes to Rock Properties
Raypath P6_R13-200
-180
-160
-140
-120
-100
-80
-60
-40
-20
0
20
30/0
5/19
97
29/0
8/19
97
28/1
1/19
97
27/0
2/19
98
29/0
5/19
98
28/0
8/19
98
27/1
1/19
98
26/0
2/19
99
28/0
5/19
99
27/0
8/19
99
26/1
1/19
99
25/0
2/20
00
26/0
5/20
00
25/0
8/20
00
24/1
1/20
00
23/0
2/20
01
25/0
5/20
01
24/0
8/20
01
23/1
1/20
01
22/0
2/20
02
24/0
5/20
02
23/0
8/20
02
22/1
1/20
02
21/0
2/20
03
23/0
5/20
03
22/0
8/20
03
Vel
oci
ty C
han
ge
(m/s
)
-5.5
-4.5
-3.5
-2.5
-1.5
-0.5
0.5
1.5
2.5
3.5
4.5
% C
han
ge
in Y
ou
ng
s M
od
ulu
s
Raypath P4_R8
-60
-40
-20
0
20
40
60
30/0
5/19
97
29/0
8/19
97
28/1
1/19
97
27/0
2/19
98
29/0
5/19
98
28/0
8/19
98
27/1
1/19
98
26/0
2/19
99
28/0
5/19
99
27/0
8/19
99
26/1
1/19
99
25/0
2/20
00
26/0
5/20
00
25/0
8/20
00
24/1
1/20
00
23/0
2/20
01
25/0
5/20
01
24/0
8/20
01
23/1
1/20
01
22/0
2/20
02
24/0
5/20
02
23/0
8/20
02
22/1
1/20
02
21/0
2/20
03
23/0
5/20
03
22/0
8/20
03
Vel
oci
ty C
han
ge
(m/s
)
-3
-1.5
0
1.5
3
4.5
% C
ha
ng
e i
n Y
ou
ng
s M
od
ulu
s
• Raypath P6_R13
• Large decrease as clay key excavated and bulkhead built.
• Peaks due to evaporation experiment.
• Increase during heating.
• Raypath P4_R8
• Increase during excavation.
• Decrease during pressurization.
• Large increase during heating.
-200
-180
-160
-140
-120
-100
-80
-60
-40
-20
0
20
30/0
5/19
97
29/0
8/19
97
28/1
1/19
97
27/0
2/19
98
29/0
5/19
98
28/0
8/19
98
27/1
1/19
98
26/0
2/19
99
28/0
5/19
99
27/0
8/19
99
26/1
1/19
99
25/0
2/20
00
26/0
5/20
00
25/0
8/20
00
24/1
1/20
00
23/0
2/20
01
25/0
5/20
01
24/0
8/20
01
23/1
1/20
01
22/0
2/20
02
24/0
5/20
02
23/0
8/20
02
22/1
1/20
02
21/0
2/20
03
23/0
5/20
03
22/0
8/20
03
-5.5
-4.5
-3.5
-2.5
-1.5
-0.5
0.5
1.5
2.5
3.5
4.5
Vp Vs
E Clay Key Excavation
Clay Bulkhead Built Sand in Chamber
Water in Chamber Pressure Increase
Temperature Increase
SW NE
P4
R8
SW NE
R13P6
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How do Earthquakes Scale?
Mw = -4 Mw = 8
URL AE
(Mw~-7 to -5)
URL MS
(Mw~-4 to -1)(from McGarr, 1999)
Stre
ss D
rop
Moment Magnitude
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Some questions left unanswered
• Can we use geophysical techniques to estimate permeability?
• How do we predict and validate the long term strength and behaviour of fractured rock?
• How do earthquake processes scale?