1st Edition

Guidelines for Open Pit Slope Design

Edited By

John Read


Peter Stacey

ISBN 9780415874410
Published December 19, 2009 by CRC Press
510 Pages

USD $210.00

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Book 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.

Table of 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

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 Post blast inspection 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


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





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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.

Peter Stacey has accumulated over 45 years of international experience in the geotechnical aspects of open pits, including slope design and implementation, as well as project management. He holds a B.Sc. Hons. degree in Geology, a D.I.C. from Imperial College, London, and is a registered engineer in Canada and the UK. After working for the Geological Survey of Sweden and subsequently with the Iron Ore Company of Canada as Supervisor – Geotechnical Engineering, Mr Stacey joined Golder Associates Ltd., based in Vancouver, Canada. During his 29 years with Golder, Mr Stacey worked primarily in the areas of pit slope design and the application of geotechnical engineering to the operational aspects of open pit mines around the world.
In 2003, Mr Stacey formed Stacey Mining Geotechnical Ltd. to concentrate on independent review consulting. In this capacity, he is currently engaged in performing geotechnical reviews for a number of international mining and consulting companies, and is a member of Geotechnical Review Boards for several large open pit operations. In addition, he leads courses in pit slope design and implementation.