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Guidelines for Open Pit Slope Design

Edited by John Read, Peter Stacey

CRC Press – 2009 – 510 pages

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    978-0-415-87441-0
    November 18th 2009

Description

Guidelines for Open Pit Slope Design is a comprehensive account of the open pit slope design process. Created as an outcome of the Large Open Pit (LOP) project, an international research and technology transfer project on the stability of rock slopes in open pit mines, this book provides an up-to-date compendium of knowledge of the slope design processes that should be followed and the tools that are available to aid slope design practitioners.

This book links innovative mining geomechanics research into the strength of closely jointed rock masses with the most recent advances in numerical modelling, creating more effective ways for predicting the reliability of rock slopes in open pit mines. It sets out the key elements of slope design, the required levels of effort and the acceptance criteria that are needed to satisfy best practice with respect to pit slope investigation, design, implementation and performance monitoring.

This book will assist open pit mine slope design practitioners, including engineering geologists, geotechnical engineers, mining engineers and civil engineers and mine managers, in meeting stakeholder requirements for pit slopes that are stable, in regards to safety, ore recovery and financial return, for the required life of the mine.

Contents

Preface and acknowledgments

1 Fundamentals of slope design

Peter Stacey

1.1 Introduction

1.2 Pit slope designs

1.2.1 Safety/social factors

1.2.2 Economic factors

1.2.3 Environmental and regulatory factors

1.3 Terminology of slope design

1.3.1 Slope configurations

1.3.2 Instability

1.3.3 Rockfall

1.4 Formulation of slope designs

1.4.1 Introduction

1.4.2 Geotechnical model (Chapter 7)

1.4.3 Data uncertainty (Chapter 8)

1.4.4 Acceptance criteria (Chapter 9)

1.4.5 Slope design methods (Chapter 10)

1.4.6 Design implementation (Chapter 11)

1.4.7 Slope evaluation and monitoring (Chapter 12)

1.4.8 Risk management (Chapter 13)

1.4.9 Closure (Chapter 14)

1.5 Design requirements by project level

1.5.1 Project development

1.5.2 Study requirements

1.6 Review

1.6.1 Overview

1.6.2 Review levels

1.6.3 Geotechnically competent person

1.7 Conclusion

2 Field data collection

John Read, Jarek Jakubec and Geoff Beale

2.1 Introduction

2.2 Outcrop mapping and logging

2.2.1 Introduction

2.2.2 General geotechnical logging

2.2.3 Mapping for structural analyses

2.2.4 Surface geophysical techniques

2.3 Overburden soils logging

2.3.1 Classification

2.3.2 Strength and relative density

2.4 Core drilling and logging

2.4.1 Introduction

2.4.2 Planning and scoping

2.4.3 Drill hole location and collar surveying

2.4.4 Core barrels

2.4.5 Downhole surveying

2.4.6 Core orientation

2.4.7 Core handling and documentation

2.4.8 Core sampling, storage and preservation

2.4.9 Core logging

2.4.10 Downhole geophysical techniques

2.5 Groundwater data collection

2.5.1 Approach to groundwater data collection

2.5.2 Tests conducted during RC drilling

2.5.3 Piezometer installation

2.5.4 Guidance notes: installation of test wells for pit slope depressurisation

2.5.5 Hydraulic tests

2.5.6 Setting up pilot depressurisation trials

2.6 Data management

Endnotes

3 Geological model

John Read and Luke Keeney

3.1 Introduction

3.2 Physical setting

3.3 Ore body environments

3.3.1 Introduction

3.3.2 Porphyry deposits

3.3.3 Epithermal deposits

3.3.4 Kimberlites

3.3.5 VMS deposits

3.3.6 Skarn deposits

3.3.7 Stratabound deposits

3.4 Geotechnical requirements

3.5 Regional seismicity

3.5.1 Distribution of earthquakes

3.5.2 Seismic risk

3.6 Regional stress

4 Structural model

John Read

4.1 Introduction

4.2 Model components

4.2.1 Major structures

4.2.2 Fabric

4.3 Geological environments

4.3.1 Introduction

4.3.2 Intrusive

4.3.3 Sedimentary

4.3.4 Metamorphic

4.4 Structural modelling tools

4.4.1 Solid modelling

4.4.2 Stereographic projection

4.4.3 Discrete fracture network modelling

4.5 Structural domain definition

4.5.1 General guidelines

4.5.2 Example application

5 Rock mass model

Antonio Karzulovic and John Read

5.1 Introduction

5.2 Intact rock strength

5.2.1 Introduction

5.2.2 Index properties

5.2.3 Mechanical properties

5.2.4 Special conditions

5.3 Strength of structural defects

5.3.1 Terminology and classification

5.3.2 Defect strength

5.4 Rock mass classification

5.4.1 Introduction

5.4.2 RMR, Bieniawski

5.4.3 Laubscher IRMR and MRMR

5.4.4 Hoek-Brown GSI

5.5 Rock mass strength

5.5.1 Introduction

5.5.2 Laubscher strength criteria

5.5.3 Hoek-Brown strength criterion

5.5.5 Directional rock mass strength

5.5.6 Synthetic rock mass model

6 Hydrogeological model

Geoff Beale

6.1 Hydrogeology and slope engineering

6.1.1 Introduction

6.1.2 Porosity and pore pressure

6.1.3 General mine dewatering and localised pore pressure control

6.1.4 Making the decision to depressurise

6.1.5 Developing a slope depressurisation program

6.2 Background to groundwater hydraulics

6.2.1 Groundwater flow

6.2.2 Porous-medium (intergranular) groundwater settings

6.2.3 Fracture-flow groundwater settings

6.2.4 Influences on fracturing and groundwater

6.2.5 Mechanisms controlling pore pressure reduction

6.3 Developing a conceptual hydrogeological model of pit slopes

6.3.1 Integrating the pit slope model into the regional model

6.3.2 Conceptual mine scale hydrogeological model

6.3.3 Detailed hydrogeological model of pit slopes

6.4 Numerical hydrogeological models

6.4.1 Introduction

6.4.2 Numerical hydrogeological models for mine scale dewatering applications

6.4.3 Pit slope scale numerical modelling

6.4.4 Numerical modelling for pit slope pore pressures

6.4.5 Coupling pore pressure and geotechnical models

6.5 Implementing a slope depressurisation program

6.5.1 General mine dewatering

6.5.2 Specific programs for control of pit slope pressures

6.5.3 Selecting a slope depressurisation method

6.5.4 Use of blasting to open up drainage pathways

6.5.5 Water management and control

6.6 Areas for future research

6.6.1 Introduction

6.6.2 Relative pore pressure behaviour between high-order and low-order fractures

6.6.3 Standardising the interaction between pore pressure and geotechnical models

6.6.4 Investigation of transient pore pressures

6.6.5 Coupled pore pressure and geotechnical modelling

7 Geotechnical model

Alan Guest and John Read

7.1 Introduction

7.2 Constructing the geotechnical model

7.2.1 Required output

7.2.2 Model development

7.2.3 Building the model

7.2.4 Block modelling approach

7.3 Applying the geotechnical model

7.3.1 Scale effects

7.3.2 Classification systems

7.3.3 Hoek-Brown rock mass strength criterion

7.3.4 Pore pressure considerations

8 Data uncertainty

John Read

8.1 Introduction

8.2 Causes of data uncertainty

8.3 Impact of data uncertainty

8.4 Quantifying data uncertainty

8.4.1 Overview

8.4.2 Subjective assessment

8.4.3 Relative frequency concepts

8.5 Reporting data uncertainty

8.5.1 Geotechnical reporting system

8.5.2 Assessment criteria checklist

8.6 Summary and conclusions

9 Acceptance criteria

Johan Wesseloo and John Read

9.1 Introduction

9.2 Factor of safety

9.2.1 FoS as a design criterion

9.2.2 Tolerable factors of safety

9.3 Probability of failure

9.3.1 PoF as a design criterion

9.3.2 Acceptable levels of PoF

9.4 Risk model

9.4.1 Introduction

9.4.2 Cost–benefit analysis

9.4.3 Risk model process

9.4.4 Formulating acceptance criteria

9.4.5 Slope angles and levels of confidence

9.5 Summary

10 Slope design methods

Loren Lorig, Peter Stacey and John Read

10.1 Introduction

10.1.1 Design steps

10.1.2 Design analyses

10.2 Kinematic analyses

10.2.1 Benches

10.2.2 Inter-ramp slopes

10.3 Rock mass analyses

10.3.1 Overview

10.3.2 Empirical methods

10.3.3 Limit equilibrium methods

10.3.4 Numerical methods

10.3.5 Summary recommendations

11 Design implementation

Peter Williams, John Floyd, Gideon Chitombo and Trevor Maton

11.1 Introduction

11.2 Mine planning aspects of slope design

11.2.1 Introduction

11.2.2 Open pit design philosophy

11.2.3 Open pit design process

11.2.4 Application of slope design criteria in mine design

11.2.5 Summary and conclusions

11.3 Controlled blasting

11.3.1 Introduction

11.3.2 Design terminology

11.3.3 Blast damage mechanisms

11.3.4 Influence of geology on blast-induced damage

11.3.5 Controlled blasting techniques

11.3.6 Delay configuration

11.3.7 Design implementation

11.3.8 Performance monitoring and analysis

11.3.8.1 Post blast inspection

11.3.8.2 Post excavation inspection and batter quantification

11.3.9 Design refinement

11.3.10 Design platform

11.3.11 Planning and optimisation cycle

11.4 Excavation and scaling

11.4.1 Excavation

11.4.2 Scaling and bench cleanup

11.4.3 Evaluation of bench design achievement

11.5 Artificial support

11.5.1 Basic approaches

11.5.2 Stabilisation, repair and support methods

11.5.3 Design considerations

11.5.4 Economic considerations

11.5.5 Safety considerations

11.5.6 Specific situations

11.5.7 Reinforcement measures

11.5.8 Rockfall protection measures

12 Performance assessment and monitoring

Mark Hawley, Scott Marisett, Geoff Beale and Peter Stacey

12.1 Assessing slope performance

12.1.2 Geotechnical model validation and refinement

12.1.3 Bench performance

12.1.4 Inter-ramp slope performance

12.1.5 Overall slope performance

12.1.6 Summary and conclusions

12.2 Slope monitoring

12.2.1 Introduction

12.2.2 Movement monitoring systems

12.2.3 Guidelines on the execution of monitoring programs

12.3 Ground control management plans

12.3.1 Introduction

12.3.2 Slope stability plan

13 Risk management

Ted Brown and Alison Booth

13.1 Introduction

13.1.1 Background

13.1.2 Purpose and content of this chapter

13.1.3 Sources of Information

13.2 Overview of risk management

13.2.1 Definitions

13.2.2 General risk management process

13.2.3 Risk management in the minerals industry

13.3 Geotechnical risk management for open pit slopes

13.4 Risk assessment methodologies

13.4.1 Approaches to risk assessment

13.4.2 Risk identification

13.4.3 Risk analysis

13.4.4 Risk evaluation

13.5 Risk mitigation

13.5.1 Overview

13.5.2 Hierarchy of controls

13.5.3 Geotechnical control measures

13.5.4 Mitigation plans

13.5.5 Monitoring, review and feedback

14 Open pit closure

Dirk van Zyl

14.1 Introduction

14.2 Mine closure planning for open pits

14.2.1 Introduction

14.2.2 Closure planning for new mines

14.2.3 Closure planning for existing mines

14.2.4 Risk assessment and management

14.3 Open pit closure planning

14.3.1 Closure goals and criteria

14.3.2 Site characterisation

14.3.3 Ore body characteristics and mining approach

14.3.4 Surface water diversion

14.3.5 Pit water balance

14.3.6 Pit lake water quality

14.3.7 Ecological risk assessment

14.3.8 Pit wall stability

14.3.9 Pit access

14.3.10 Reality of open pit closure

14.4 Open pit closure activities and post-closure monitoring

14.4.1 Closure activities

14.4.2 Post-closure monitoring

14.5 Conclusions

Endnotes

Appendix 1: Groundwater data collection

Appendix 2: Essential statistical and probability theory

Appendix 3: Influence of in situ stresses on open pit design

Appendix 4: Risk management: geotechnical hazard checklists

Appendix 5: Example regulations for open pit closure

Terminology and definitions

References

Index

Author Bio

Dr. Read has over 40 years experience as a practitioner and consultant in the mining industry, with special interests and expertise in rock slope stability. In 1990 Dr Read began his own geotechnical engineering practice. Since then he has specialised in slope stability and open pit mine slope design and investigation tasks in Australia, Fiji, Papua New Guinea, Brazil, Argentina, Chile, Canada, South Africa, and Zambia. From 1994 to 2004 he was Deputy Chief of CSIRO Exploration & Mining and Executive Manager of the Queensland Centre for Advanced Technologies, Brisbane.

Name: Guidelines for Open Pit Slope Design (Hardback)CRC Press 
Description: Edited by John Read, Peter Stacey. Guidelines for Open Pit Slope Design is a comprehensive account of the open pit slope design process. Created as an outcome of the Large Open Pit (LOP) project, an international research and technology transfer project on the stability of rock slopes in...
Categories: Geology - Earth Sciences, Mining, Mineral & Petroleum Engineering