rock mechanics modelling and engineering design · rock mechanics modelling and engineering design...
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![Page 1: Rock Mechanics Modelling and Engineering Design · Rock Mechanics Modelling and Engineering Design John A Hudson Lecture 8 . F 1 F 2 F 3 F n Fractures Intact rock Boundary conditions](https://reader030.vdocuments.us/reader030/viewer/2022021716/5e46d70cee505034796e3e8b/html5/thumbnails/1.jpg)
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Rock Mechanics Modelling
and Engineering Design
John A Hudson
Lecture 8
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F1
F2
F3
Fn
Fractures
Intact rock
Boundary
conditions
Excavation
Water flow
How do we model loading a rock mass on the surface or
excavating inside a rock mass?
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We will construct a diagram/flowchart based on these four
methods, classified according to their complexity.
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And we will think about two levels:
1:1 mappingthe problem is modelled directly; and
not 1:1 mappingthe problem is not modelled directly.
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Use of
pre-existing
standard
methods
Precedent type
analyses and
modifications
Method A
Li S.H., Wu X.Y., & Ma F.S.
(1998) IJRMMS. Application of
Precedent Type Analysis (PTA)
in the Construction of Ertan
Hydro-Electric Station, China.
‘Simple’
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Analytical
methods,
stress-based
e.g. the Kirsch
solution
Rock mass
classification,
RMR, Q, GSI
Level 1
1:1 mapping
Level 2
Not 1:1 mapping
Method B
Nick Barton:
“We have to damp down
the mechanisms in order to
make the model work”
Low to
medium
complexity
5
v
h
a
r
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Why we need rock
mass classification
Foundation
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Basic
numerical
methods,
FEM, BEM,
DEM, hybrid
Basic systems
approaches,
databases,
expert systems
Level 1
1:1 mapping
Level 2
Not 1:1 mapping
Method C
Medium to
high
complexity
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Extended
numerical
methods,
e.g. coupled
THMC
Fully
integrated
systems
approaches,
internet-based
Level 1
1:1 mapping
Level 2
Not 1:1 mapping
Method D
e.g. DECOVALEX research
programmes for radioactive
waste disposal
-with the long term aim of
producing fully-coupled
thermo-hydro-mechanical-
chemical numerical models
Next slide
Complicated
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Method D
Level 2
possibilities
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Use of
pre-existing
standard
methods
Analytical
methods,
stress-based
Basic
numerical
methods, FEM,
BEM, DEM,
hybrid
Extended
numerical
methods,
fully-coupled
models
Precedent type
analyses and
modifications
Rock mass
classification,
RMR, Q, GSI
Database
expert
systems, &
other systems
approaches
Integrated
systems
approaches,
internet-based
Objective
Construction
Site
Invest-
igation
Level 1
1:1 mapping
Level 2
Not 1:1 mapping
Design based on forward analysis Design based on back analysis
Method A Method B Method C Method D
Leading to this composite flowchart
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The content of the
following slides in this
lecture can be found in
the 2011 book by Feng
and Hudson
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Some of the questions that stimulated us as the work by
the ISRM Commission developed…
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The Figure 2.1 flowchart summarising the modelling approaches
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Applications
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Design of a hydroelectric
powerhouse cavern:
Shuibuya project in China
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Initial design
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Initial design
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Cracking of shotcrete
Spalling
Maximum principal
stress
Maximum principal
stress
Location of typical local failures (at Jinping II
powerhouse after Excavation Stage IV) 22
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Final design
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What information do we need to use these eight approaches?
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Use of
pre-existing
standard
methods
Analytical
methods,
stress-based
Basic
numerical
methods, FEM,
BEM, DEM,
hybrid
Extended
numerical
methods,
fully-coupled
models
Precedent type
analyses and
modifications
Rock mass
classification,
RMR, Q, GSI
Database
expert
systems, &
other systems
approaches
Integrated
systems
approaches,
internet-based
Objective
Construction
Site
Invest-
igation
Level 1
1:1 mapping
Level 2
Not 1:1 mapping
Design based on forward analysis Design based on back analysis
Method A Method B Method C Method D
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Principles for modelling
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![Page 27: Rock Mechanics Modelling and Engineering Design · Rock Mechanics Modelling and Engineering Design John A Hudson Lecture 8 . F 1 F 2 F 3 F n Fractures Intact rock Boundary conditions](https://reader030.vdocuments.us/reader030/viewer/2022021716/5e46d70cee505034796e3e8b/html5/thumbnails/27.jpg)
Use of
pre-existing
standard
methods
Analytical
methods,
stress-based
Basic
numerical
methods, FEM,
BEM, DEM,
hybrid
Extended
numerical
methods,
fully-coupled
models
Precedent type
analyses and
modifications
Rock mass
classification,
RMR, Q, GSI
Database
expert
systems, &
other systems
approaches
Integrated
systems
approaches,
internet-based
Objective
Construction
Site
Invest-
igation
Level 1
1:1 mapping
Level 2
Not 1:1 mapping
Design based on forward analysis Design based on back analysis
Method A Method B Method C Method D
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![Page 28: Rock Mechanics Modelling and Engineering Design · Rock Mechanics Modelling and Engineering Design John A Hudson Lecture 8 . F 1 F 2 F 3 F n Fractures Intact rock Boundary conditions](https://reader030.vdocuments.us/reader030/viewer/2022021716/5e46d70cee505034796e3e8b/html5/thumbnails/28.jpg)
Use of
pre-existing
standard
methods
Analytical
methods,
stress-based
Basic
numerical
methods, FEM,
BEM, DEM,
hybrid
Extended
numerical
methods,
fully-coupled
models
Precedent type
analyses and
modifications
Rock mass
classification,
RMR, Q, GSI
Database
expert
systems, &
other systems
approaches
Integrated
systems
approaches,
internet-based
Objective
Construction
Site
Invest-
igation
Level 1
1:1 mapping
Level 2
Not 1:1 mapping
Design based on forward analysis Design based on back analysis
Method A Method B Method C Method D
![Page 29: Rock Mechanics Modelling and Engineering Design · Rock Mechanics Modelling and Engineering Design John A Hudson Lecture 8 . F 1 F 2 F 3 F n Fractures Intact rock Boundary conditions](https://reader030.vdocuments.us/reader030/viewer/2022021716/5e46d70cee505034796e3e8b/html5/thumbnails/29.jpg)
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The Fig.
3.12
design
flowchart
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Principles for numerical code implementation
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Laxiwa project
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The Yellow River, China
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Computer models and
choice of cavern orientation
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Main powerhouse
Transformer
chamber
A1-7
A2-7
A2-5
P1
P3 P4
ZBA-5 ZBA-2
A1 A2
A4
A5
ZBA
A4-7
A5-1
A5-6
P2
Monitoring points chosen
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Questions to be asked
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End of Lecture 8
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