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The Future for Rock Mechanics

and Rock Engineering

John A Hudson

Lecture 14

International Society for Rock Mechanics (ISRM)

Paper given at the 12th ISRM Congress, Beijing, Oct. 2011

The Next 50 Years of the ISRM and

Anticipated Future Progress

in Rock Mechanics

John A Hudson

ISRM President 2007 2011

Imperial College of Science, Technology and Medicine, London, UK

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This presentation on the 50-year anticipated future

of the ISRM and rock mechanics forms part of the

ISRM 50-year anniversary celebrations and

complements the preceding paper by E T Brown on

the previous 50 years of the ISRM.

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I will use two methods to predict the future of

the ISRM and rock mechanics:

1. Using the past and present future

2. Blue skies thinking

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In the first approach, we adopt the approach of

Hippocrates over 2000 years ago:

“Consider the past,

diagnose the present,

foretell the future.”

Hippocrates, 460-377 BC

温故知新

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F1

F2

F3

Fn

Fractures

Intact rock

Boundary

conditions

Excavation

Water flow

• Geology

• Rock stress

• Intact rock

• Fractures

• Rock mass properties

• Water flow

• Modelling

• Support

• Excavation

Some of the component subjects in rock

mechanics and rock engineering:

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Geology

There will be much more integration of geological features

into the modelling that supports rock engineering

designin order to make the modelling more realistic.

F1

F2

F3

Fn

Fractures

Intact rock

Boundary

conditions

Excavation

Water flow

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Rock Stress

There will be a much better understanding of the rock stress

distribution at a sitewhich we don’t always have currently.

F1

F2

F3

Fn

Fractures

Intact rock

Boundary

conditions

Excavation

Water flow

150 m depth, from Valli, Hakala and Kuula

(2011)

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• Tectonic scale and

regional stresses

• Site scale

• Excavation scale

• Borehole/measurement scale

• Microscopic scale

Different scales

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Fractures

Considerable work has already been done on the

geometrical and mechanical properties of fractures, but

much more is required.

Porteau Bluff on

Highway 99

North of Vancouver,

Canada

F1

F2

F3

Fn

Fractures

Intact rock

Boundary

conditions

Excavation

Water flow

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Rock mass properties

Similarly, we now have a good

understanding of estimating the

mechanical properties of rock

masses but,

in the future, there will also be

more emphasis on the influence

of fractures, inhomogeneity and

anisotropy aspects.

F1

F2

F3

Fn

Fractures

Intact rock

Boundary

conditions

Excavation

Water flow

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Water flow

Characterising and predicting water flow through a

fractured rock mass is not easy. Considerable progress

has been made, but much more work will be done in the

future.

F1

F2

F3

Fn

Fractures

Intact rock

Boundary

conditions

Excavation

Water flow

Mountsorrel granodiorite quarry, UK

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Modelling

This has developed extensively in the last 50 years

and will continue to do so in the next 50 years.

0

5

10

15

20

25

30

35

40

0 0.5 1 1.5 2

Strain (0.001)

Str

es

s (

MP

a)

H/W=3

H/W=1.5

H/W=1

H/W=0.67

H/W=0.5

H/W=3 H/W=1.5 H/W=1 H/W=2 H/W=0.5

Modelled using the RFPA code : Chun’an Tang et al.

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Support/Reinforcement

This has developed extensively in the last 50 yearsand

will continue to do so in the next 50 years.

It is difficult to see how support

can be significantly improved:

there are already good

techniques for holding the rock

back and for reinforcing it.

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Excavation

Mechanised excavation has been

a major breakthrough, but there is

still huge potential…

Robbins machine, Kielder Tunnel, UK, 1970s

Energy input

Time

Blasting: large amounts of energy input at widely spaced intervals

TBM: smaller amounts of energy input essentially constantly

Increasing the input energy would enable much faster penetration and advance rates

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Blue Skies

The two methods being used to predict the future of

the ISRM and rock mechanics are

1. Using the past and present future, and

2. Blue skies thinking.

So let’s now try Blue Skies…

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Growth in computing power

Next 50-100 years

50 years from now

All human brains

One human brain One mouse brain

One insect brain

Now

Ca

lcu

latio

ns p

er

se

co

nd

pe

r $

10

00

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It is now recognised that

Geological-Thermal-Hydrological-

Mechanical-Chemical-Engineering modelling

is required to fully understand the mechanisms

that occur in the rock mass.

Geological: site geometry, lithology, fractures

Thermal: heat loads, heat flow

Hydrological: water pressures, water flow

Mechanical: rock stress, stiffness, strength

Chemical: water chemistry, swelling rocks

Engineering: effects of excavation

Hopefully, we will have a fully-coupled model…

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What will happen to books?

Microsoft have announced that they will make 25 million

pages of books and documents available from the British

Library online and free of charge.

Google Print – same things for US libraries…

…and so we will all use the Internet.

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Publishing – Information communication

Computers will compile papers

about the cumulative advances

in rock mechanics using all the

papers published each year.

If computers become authors, how should they be identified,

or identify themselves?

Will we be able to tell if the author is human or a computer?

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Computer design of rock engineering facilities

At the moment, we as human engineers decide that we need

a rock engineering facility, then we make preparations,

operate a design model, evaluate the consequences, etc. Is

it possible that all this could be computerised one day?

Could the computer decide what engineering facilities are

required, then indicate what site investigation is required,

then choose the most appropriate numerical model from its

library, and then decide on the optimal engineering design?

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Attendance at

conferences

It will be an option whether we attend a conference

physically or electronically.

Some people will wish to attend physically, but electronic

attendance will be preferred by many others.

This has many advantages, not least of which is that one

could attend many more conferences.

What about Short Courses like this one?!! 22

Summary of future trends in rock mechanics

and rock engineering

• Improved methods of accessing/collating information

• More emphasis on geophysical methods in SI

• More integration of subjects (e.g. GTHMCB)

• More international co-operation

• More use of neural network ‘intelligent’ computer

programs

• Larger, deeper and longer excavations

• Emphasis on ‘environmental’ aspects

• Increased rate of mechanised excavation

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Finally, what is likely to happen to the ISRM in the

next 50 years?

There are two major

possibilities:

Scenario A

It will continue to be

successful and expand

both in terms of

membership and scope

Scenario B

It will disband because all the

existing benefits will be

available to individuals

through the Internet

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But, we have to work together – no one person can have

sufficient knowledge to understand the whole system in detail.

Unfortunately, we tend to work in our own subject areas

(cf. geology, rock and soil mechanics).

British Prime Minister, David Cameron: “We’re all in this together.”

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Modelling approaches

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

The future

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Are we able to create a computerised virtual model of a rock

mass with all the GTHMCBE elements and then model a virtual

underground research laboratory and conduct virtual

experiments? e.g. the influence of scale.

Real Virtual

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The future is the Internet, and maybe the Semantic Web

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The Semantic Web

(‘Semantic’: understanding the meaning of information)

A method of representing semantically structured

knowledge. It extends the network of hyper-linked human-

readable web pages by inserting machine-readable

metadata about pages and how they are related to each

other, enabling automated agents to access the Web more

intelligently and perform tasks on behalf of users.

Computers will be able to gather the data, and one day

soon be able to write papers!

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• Where do we obtain the input information for the

model?

• What is the balance between generic and specific

information?

• How do we incorporate ‘memory’ into the model?

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Incorporating Memory into Rock Mechanics Modelling

and Rock Engineering Design

John A Hudson

Department of Earth Science and Engineering, Imperial College,

London, UK

Xia-Ting Feng

Institute of Rock and Soil Mechanics, Chinese Academy of

Sciences, Wuhan, China

ISRM Commission on Rock Engineering Design Methodology

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Abstract: This paper addresses the problem of obtaining the

information to support rock mechanics modelling and rock

engineering design.

A large amount of relevant material exists worldwide on

previous rock parameter determinations, modelling

exercises, design work, and construction projects. However,

the information learnt from these activities is not easily

accessible and useable, i.e. there has been no attempt to

develop a ‘corporate memory’ system for rock mechanics

and rock engineering.

A structure for such a system is outlined comprising tables of

intact and rock mass properties, libraries of standard and

case example modelling solutions, and libraries of design

and construction case examples. The procedure for initial

implementation of the memory system under the aegis of the

ISRM is described.

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Objective

Method A

Lab a

nd f

ield

tests

Use of

pre-existing

standard

methods

Construction and monitoring

Design based on forward analysis Design based on back analysis

Precedent type

analyses and modifications

Analytical methods,

stress-based

Integrated systems

approaches, internet-based

Site investig

ation

Level 2 Not 1:1

mapping

Level 1 1:1 mapping

Method B Method C Method D

Basic numerical methods,

FEM, BEM, DEM, hybrid

Extended numerical methods,

fully-coupled models

Rock mass

classification

RMR, Q,

GSI, BQ

Database expert

systems,& other

systems approaches

What information do we need

to support these boxes?

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Declarative knowledge Procedural knowledge

Specific knowledge learnt from

experience and generic knowledge

abstracted from many experiences

Skills knowledge such as touch-typing,

operating a computer, recognising when

there is likely to be a roof fall

Episodic

knowledge

Semantic

knowledge

e.g. knowledge

derived from

observation of a

cavern roof fall

e.g. knowledge of

rock mechanics

terminology

and units

The structure of human memory

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A 'CORPORATE MEMORY' SYSTEM

FOR ROCK MECHANICS INFORMATION

ROCK PROPERTY

INFORMATION

CONSTRUCTION

EXPERIENCE

MODELLING

EXERCISES

LABOR-

ATORY

TESTING

IN SITU

TESTING

GENERIC

MOD-

ELLING

SPECIFIC

MOD-

ELLING

DESIGN

CASE

EXAMPLES

CONST-

UCTION

CASE

EXAMPLES

COHERENCY CONDITIONING OF THE MODULES ABOVE

SO THAT THE INFORMATION CAN BE USED DIRECTLY

TABLES OF

INTACT ROCK

PROP-

ERTIES

TABLES OF

ROCK MASS

PROP-

ERTIES

LIBRARY OF

STANDARD

MODELLING

SOLUTIONS

LIBRARY OF

CASE

EXAMPLE

MODELLING

SOLUTIONS

LIBRARY OF

DESIGN

CASE

EXAMPLES

LIBRARY OF

CONST-

RUCTION

CASE

EXAMPLES

INTERROGATION AND RETRIEVAL SYSTEM

The three main

components

The six main subjects

The six main sources

of information

The required system

Converting the

information into a

useable form

The required corporate

memory system

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End of Lecture 14

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