Ground Support Technology for Highly Stressed Excavations: Integrated Theoretical, Laboratory, and Field Research

Cover
Half Title
Title
Copyright
Contents
About the Authors
Foreword
Preface
Acknowledgements
Chapter 1 Introduction
1.1 Introduction
1.2 The Process of Support and Reinforcement
1.3 Brief History of Ground Support Technology
1.4 Scope and Contents of This Book
Chapter 2 Terminology
2.1 Introduction
2.2 Reinforcement System Response
2.3 Continuous Mechanically Coupled
2.4 Continuous Frictionally Coupled
2.5 Discrete Mechanically or Frictionally Coupled
2.6 The Load Transfer Concept
2.7 The Embedment Length Concept
2.8 Materials Behaviour Terminology
2.8.1 Elastic
2.8.2 Plastic
2.8.3 Brittle
2.8.4 Ductile
2.8.5 Resilience
2.8.6 Toughness
2.8.7 Yield
2.8.8 Stiffness
2.9 Performance Indicators of Capacity
2.10 Surface Support System Response
2.10.1 Type of Support Systems
2.10.1.1 Point Support Systems
2.10.1.2 Strip Support Systems
2.10.1.3 Areal Support Systems
2.10.2 Loading Mechanisms
2.10.3 Load Transfer Concepts
2.10.3.1 Point Support Systems
2.10.3.2 Strip and Areal Support Systems
Chapter 3 Probabilistic Simulation of Rock Mass Demand
3.1 Introduction
3.2 Rock Mass Characterization
3.2.1 Geotechnical Mapping of Underground Exposures
3.3 Rock Mass Model
3.4 Deterministic Assessment of Rock Mass Instabilities
3.5 Probabilistic Assessment of Rock Mass Instabilities
3.5.1 Interpretation of Results
Chapter 4 Ground Support Mechanics
4.1 Introduction
4.2 Reinforcement Response
4.2.1 Load Transfer within the Collar Region
4.2.2 Load Transfer along the Element and at the Toe Anchor Region
4.3 Surface Support Response
4.4 Failure Geometry
4.5 Surface Layer Toughness
4.6 Ground Support Scheme
Chapter 5 Ground Support Design
5.1.Introduction
5.2.Rock Mass Characterization
5.2.1.Structure
5.2.2.Strength
5.3.Tunnel Instability
5.2.1.Spalling Failure
5.2.2.Structurally Controlled Failure
5.2.3.Damage and Deformation Prior to Violent Failure
5.3.Ejection Velocity
5.4.Ground Support Demand
5.4.1.Shallow Depth of Failure (Spalling)
5.4.2.Structurally Controlled Depth of Failure
5.5.Ground Support Capacity
5.5.1.Ground Support Design for Extremely High Demand Conditions
Chapter 6 Laboratory Testing
6.1 Introduction
6.2 Testing Documentation
6.3 Component Testing
6.4 Element Testing
6.4.1 Prestressing Strand
6.4.2 Solid Threaded Bar
6.5 Internal Fixture Testing
6.5.1 Slot and Wedge Anchors
6.5.2 Expansion Shell Anchors
6.5.3 Cement Grouts
6.5.4 Resin Grouts
6.6 External Fixture Testing
6.6.1 Split Tube Rings
6.6.2 Barrel and Wedge Strand Anchors
6.6.3 Plates
6.7 Systems Testing
6.7.1 Cable Bolt Pull Tests
6.7.2 Resin-Encapsulated Reinforcement Ł
6.8 WASM Dynamic Test Facility
6.8.1 Force Transfer and Displacement
6.8.2 Simulated Boreholes and Sample Installation
6.8.3 Dynamic Test Results
6.8.4 Analysis of Dynamic Test Results
6.8.5 Dynamic Testing of Mesh and Shotcrete Layers
Chapter 7 Energy Dissipation of Rock Bolts
7.1 Introduction
7.2 Momentum Transfer
7.3 Reinforcement System Load Transfer
7.4 Continuously Frictionally Coupled
7.4.1 Friction Rock Stabilizer
7.4.1.1 Static Testing
7.4.1.2 Dynamic Testing
7.4.2 Expanded Tube Bolts
7.4.2.1 Static Testing
7.4.2.2 Dynamic Testing
7.4.3 Hybrid Point Anchored Bar and Split Tube Bolts
7.4.3.1 Borehole Simulation and Installation
7.4.3.2 Dynamic Testing
7.5 Continuously Mechanically Coupled
7.5.1 Cement-Encapsulated Threaded Bar
7.5.1.1 Australian Threaded Bar
7.5.1.2 Chilean Threaded Bar
7.5.2 Resin-Encapsulated Threaded Bar
7.6 Discretely Mechanically or Frictionally Coupled
7.6.1 Cement-Encapsulated Decoupled Threaded Bar
7.6.2 Resin-Encapsulated Decoupled Posimix
7.6.3 Cement- and Resin-Encapsulated D Bolt
7.6.4 Cement- and Resin-Encapsulated Cone Bolt
7.6.5 Cement- and Resin-Encapsulated Garford Dynamic Bolt
7.6.6 Cement-Encapsulated Durabar Bolt
7.6.7 Cement-Encapsulated Yield-Lok Bolt
7.6.8 Self-Drilling Anchor Bolt
Chapter 8 Energy Dissipation of Cable Bolts
8.1 Introduction
8.2 Cement Grout
8.2.1 Physical and Mechanical Properties
8.2.1.1 Fresh Cement Paste
8.2.1.2 Hardened Cement
8.2.2 Grouting Reinforcement Boreholes
8.2.2.1 Toe-to-Collar Grouting
8.2.2.2 Mechanized Grouting
8.3 Cable Bolt Types
8.3.1 Modified Strand Cable Bolts
8.3.2 Plain Strand—15.2 mm Diameter
8.3.3 Plain Strand—17.8 mm Diameter
8.3.4 Decoupled Strand
8.3.5 Multiple Dynamic Impact Testing
8.4 Cable Bolt Plates
8.4.1 Barrel and Wedge Anchors
8.4.1.1 Anchor Installation
8.4.1.2 Anchor Mechanism and Performance
8.4.2 Dynamic Testing Results
Chapter 9 Energy Dissipation of Mesh Support
9.1 Introduction
9.2 Mesh Load Transfer
9.3 Mesh Testing
9.3.1 Boundary Conditions
9.3.2 Loading Method
9.4 Mesh Force and Displacement
9.4.1 Static Results for Welded Wire Mesh
9.4.2 Static Results for Woven Mesh
9.4.3 Dissipated Static Energy
9.4.4 Dynamic Results for Welded Wire Mesh
9.4.5 Dynamic Results for Woven Mesh
9.4.6 Dissipated Dynamic Energy
Chapter 10 Energy Dissipation of Shotcrete Support
10.1 Introduction
10.2 Shotcrete Mix Design
10.3 Material Properties
10.3.1 Cement
10.3.2 Mechanism of Hydration of Cement
10.3.3 Supplementary Cementing Materials
10.3.3.1 Silica Fume
10.3.3.2 Fly Ash
10.3.3.3 Slag Cement
10.3.4 Mixing Water
10.3.5 Aggregate
10.3.6 Fibres
10.3.6.1 Steel Fibres
10.3.6.2 Synthetic Fibres
10.3.7 Admixtures
10.3.7.1 Accelerator
10.3.7.2 Superplasticizer
10.3.7.3 Air-Entraining
10.3.7.4 Hydration Stabilizer
10.4 Shotcrete Support System
10.4.1 Rock Surface and Shotcrete Profiles
10.4.2 Deformation Mechanisms
10.5 Static Performance of Freshly Sprayed Shotcrete
10.5.1 Review of Shotcrete Early Strength
10.5.2 Shear Strength of Freshly Sprayed Shotcrete
10.5.2.1 Development of Shear Strength of Shotcrete Paste with and without the Influence of a Chemical Admixture
10.5.2.2 Development of Shear Strength of Shotcrete Paste with Various Combinations of Mixed Components
10.5.3 Structural Requirements for a Freshly Sprayed Shotcrete Layer
10.5.3.1 Requirements for Self-Support
10.5.3.2 Required Shotcrete Shear Strength for Self-Weight and Block Support
10.5.4 Safe Re-entry Time
10.6 Static Performance of Cured Shotcrete
10.6.1 Uniaxial Compressive Strength (UCS)
10.6.2 Tensile Strength
10.6.3 Tensile Bond Strength of Rock—Shotcrete Interface
10.6.4 Shear Strength
10.6.5 Toughness
10.7 Shotcrete Failure Mechanisms
10.7.1 Shotcrete Load Transfer
10.8 Large Scale Static Testing
10.9 Large Scale Dynamic Testing
10.9.1 Shotcrete Test Set-Up
10.9.2 Shotcrete Failure Mechanism
10.9.3 Shotcrete Energy Dissipation
10.9.3.1 Fibre-Reinforced Shotcrete
10.9.3.2 Mesh-Reinforced Shotcrete
Chapter 11 Dynamic Performance of Ground Support Schemes
11.1 Introduction
11.2 Load Transfer
11.3 Free Body Diagrams
11.4 Combined Reinforcement and Mesh Schemes
11.4.1 Sample Preparation and Testing
11.4.2 Data Analysis
11.4.3 Data
11.4.3.1 Cement-Encapsulated Rebar and G80/4 Mesh
11.4.3.2 Cement-Encapsulated Rebar and Welded Wire Mesh
11.4.3.3 Decoupled Posimix and Welded Wire Mesh
11.4.3.4 Decoupled Posimix and Woven Mesh
11.4.4 Summary of Energy Dissipation
11.5 Large-Scale Testing of Full-Scale Schemes
Chapter 12 Reinforced Block Analysis
12.1 Introduction
12.2 Description of the Problem
12.3 Reinforcement Response at a Block Face
12.4 Reinforcement Databases
12.4.1 A Generic Reinforcement System
12.4.2 Measurement of Reinforcement System Responses
12.4.3 Reinforcement System Simulations
12.4.4 Reinforcement System Responses
12.4.4.1 Component Properties
12.4.4.2 Interface Properties
12.4.4.3 Variations of Axial Force-Displacement Responses with Encapsulation Length
12.4.4.4 Axial Force-Displacement Responses with External Fixture and Encapsulation Lengths
12.4.5 Application of the Reinforcement Databases in Design for a Reinforced Block
12.4.5.1 Description of the Analysis
12.4.5.2 Estimation of Force-Displacement Responses
12.5 Static Analysis of a Reinforced Arbitrarily-Shaped Block
12.5.1 The Design Problem
12.5.2 Description of the Analysis Method
12.6 Dynamic Block Loading
12.6.1 Newtonian Mechanics-Based Analysis
12.6.2 Momentum-Based Analysis
12.6.3 Energy-Based Analysis
12.6.4 Summary of Dynamic Analysis Methods
12.7 Displacement Controlled Dynamic Analysis Methodology
12.8 Example of Implemented Theory
12.8.1 Description of the Analysis
12.8.2 Imposed Loading and Results
Chapter 13 Construction and Monitoring
13.1 Introduction
13.2 Induced Stress
13.3 Construction
13.3.1 Excavation Shape
13.3.2 De-Stress Blasting
13.3.2.1 Mechanics
13.3.2.2 De-stress Blasting Patterns
13.3.2.3 Explosive Energy
13.3.2.4 Micro Seismic Activity
13.3.2.5 Geotechnical Concerns
13.3.2.6 Case Study—Kanowna Belle Mine, WA, Australia
13.3.3 Construction of a High Energy Dissipation Ground Support Scheme
13.3.3.1 Clearing of Temporary Face Support
13.3.3.2 Mechanical Scaling
13.3.3.3 Structural Geological Mapping with Photogrammetry
13.3.3.4 Shotcrete Application
13.3.3.5 Primary Reinforcement Mark-Up
13.3.3.6 Installation of Primary Reinforcement and Mesh
13.3.3.7 Primary to Secondary Support Installation Sequence
13.3.3.8 Final Ground Support Scheme Arrangement
13.4 Monitoring
13.4.1 Drilling and Blasting
13.4.2 Deformation
References
Index