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Key Principles in Rock Mechanics

Lecture 1: Introduction

John A Hudson

Dept. Earth Science and Engineering

Imperial College, London, UK

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WELCOME

The content of this Short Course of 14 lectures

introduces some of the key principles of rock

mechanics.

If you are relatively new to the subject, these principles

will provide you with the knowledge to be more

confident in the office, in the laboratory and in the field

when dealing with rock mechanics and rock

engineering.

If you already have some rock mechanics knowledge,

these principles will help you to structure your

knowledge.

The principles here do not tell you everything, but they

are a good start to a subject that I have been involved

with for many years.

These lectures are coming to you from the

Department of Earth Science and Engineering,

Imperial College of Science, Technology and Medicine,

London, UK

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Imperial College,

just south of Hyde Park

in London, UK

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I want to provide you with a framework of pictures,

explanations and experiences, and hence to enhance

your memory.

For this reason, the lectures concentrate on images and

interpretation, rather than detailed uses of mathematics

and stereographic projection…

(…although some maths and stereographic images

have to be included for the explanations…)

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6 The natural material we are studying: fractured rocks

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What happens if we try to tunnel through this?

Structural geology is an important subject to help rock mechanics.

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PAST PRESENT FUTURE

Structural Geology

Rock Engineering

Interpretation of natural

processes that have

created the rock

structures we see today

Prediction of natural

geohazards, such as

volcanic eruptions,

earthquakes, landslips

Interpretation of past

engineering practice:

past successes, and

past failures

Prediction of the rock

mass response to

engineering

perturbations

PAST PRESENT FUTURE

Structural Geology

Rock Engineering

Interpretation of natural

processes that have

created the rock

structures we see today

Prediction of natural

geohazards, such as

volcanic eruptions,

earthquakes, landslips

Interpretation of past

engineering practice:

past successes, and

past failures

Prediction of the rock

mass response to

engineering

perturbations

STRUCTURAL GEOLOGY

ROCK ENGINEERING

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Structural geology + rock fractures + rock mechanics

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Rock mechanics and rock engineering:

The wide variety of types of engineering projects

Foundations Slopes Tunnels and caverns

Mine stopes Geothermal energy Waste disposal

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The generic

rock mechanics/

rock engineering

problem

F1

F2

F3

Fn

Fractures

Intact rock

Boundary

conditions

Excavation

Water flow

The sketch above

represents rock mechanics

and rock engineering.

Keep it in mind always.

Loch Lomond, Scotland: Is this slope stable? How would we know? 12

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Porteau Bluff on

Highway 99

North of Vancouver,

Canada

What are the structural geology influences

on the stability of this slope? What is the evidence of water flow?

In India, on the

way to China

How do we deal with such

rock slope instabilities?

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How stable do these slopes need to be?

Open Pit Mine, Kalgoorlie, Australia 15

Do we know enough about the rock conditions to ensure stability? 16

Natural rock slope above a village, Italy 17

Excavation of tunnels

What is the effect of

tunnelling on the

surrounding rock?

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Effect of geological

conditions on

engineering projects

From

“Geological Engineering” by

Gonzalez de Vallejo & Ferrer

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And more

complex

coupled

interactions

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From “Geological Engineering” by Gonzalez de Vallejo & Ferrer 21

End of Introductory Lecture 1

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