Rock Fracture and Blasting (eBook)

Cover 1
Title Page 4
Copyright Page 5
Contents 8
Dedication 6
About the Author 20
Preface 22
Part I - Stress Waves and Shock Waves 24
Chapter 1 - Stress Waves 26
1.1 - Coordinates, wave velocity, and particle velocity 27
1.1.1 - Coordinates 27
1.1.2 - Wave Velocity and Particle Velocity 27
1.2 - Category of stress waves in solids 28
1.2.1 - Body Waves 28
1.2.1.1 - P-Waves 28
1.2.1.2 - S-Waves 29
1.2.2 - Surface Waves 29
1.2.2.1 - Rayleigh Waves 30
1.2.2.2 - Love Waves 30
1.2.2.3 - Stoneley Waves 31
1.2.3 - Stress Waves Relevant to Stress–Strain Relation of Materials 31
1.2.3.1 - Elastic Waves 31
1.2.3.2 - Plastic Waves 31
1.2.3.3 - Shock Waves 31
1.2.4 - Other Names of Waves 31
1.2.4.1 - Seismic Waves and Vibration Waves 31
1.2.4.2 - Taylor Waves, Rarefaction Waves, and Unloading Waves 31
1.3 - Reflection and transmission of elastic waves 32
1.3.1 - Reflection of Elastic Waves on a Free Surface 32
1.3.1.1 - A P-Wave Incident on a Free Surface 32
1.3.1.2 - An S-Wave Incident on a Free Surface 32
1.3.2 - Reflection and Transmission of Elastic Waves at an Interface Between Two Media 33
1.3.2.1 - Reflection and Transmission of an Incident P-Wave on a Plane Interface 33
1.3.2.2 - Reflection and Transmission of an Incident S-Wave on a Plane Interface 33
1.3.3 - Stress Waves from Rock Blasting 33
1.4 - Theory of one-dimensional elastic stress waves 33
1.4.1 - Wave Equation in One-Dimensional Condition 33
1.4.2 - Solution of Wave Equation 35
1.5 - Stress wave analysis using a Lagrangian diagram 37
1.5.1 - Lagrangian Diagram for Elastic Waves 37
1.5.2 - Lagrangian Diagram for Elastic–Plastic Loading Waves 38
1.6 - Impact of two elastic bars 40
1.6.1 - General Case 40
1.6.2 - Special Cases 41
1.6.2.1 - Case 1: An Elastic Bar Impacts on a Rigid Wall 41
1.6.2.2 - Case 2: A Rigid Bar Impacts on an Elastic Bar 41
1.6.2.3 - Case 3: An Elastic Bar Impacts Another Elastic Bar Which Stands Still 41
1.6.2.4 - Case 4: A Hard Bar Impacts a Soft Bar 42
1.6.2.5 - Case 5: A Soft Bar Impacts a Hard Bar 42
1.7 - Energy in an impact system 42
1.7.1 - Relation Between Kinetic Energy and Strain Energy 42
1.7.2 - Energy Transmission 43
1.8 - Propagation of elastic waves in two different materials 43
1.8.1 - General Case 43
1.8.2 - Special Cases 45
1.8.2.1 - A Stress Wave Propagates from a Soft to a Hard Material 45
1.8.2.2 - A Stress Wave Propagates from a Hard to a Soft Material 45
1.9 - Wave reflection on a rigid wall and on a free surface 45
1.9.1 - On a Rigid Wall 45
1.9.2 - On a Free Surface 45
1.10 - Propagation of elastic waves in three different materials 46
1.11 - Superposition of elastic stress waves 47
1.11.1 - Superposition of Two Compressive Elastic Stress Waves 47
1.11.2 - Superposition of One Tensile Wave and One Compressive Wave 47
1.11.3 - Superposition of Two P-Waves from Two Blastholes 48
1.12 - Spalling caused by stress wave loading 48
1.12.1 - A Triangular Wave Reflected from a Free Surface 49
1.12.2 - Spalling Caused by a Triangular Wave 50
1.13 - Split Hopkinson pressure bar system 52
1.14 - Attenuation and dispersion of stress waves 53
1.14.1 - Factors Influencing Attenuation and Dispersion 53
1.14.2 - Wave Attenuation Measured at Laboratory 55
1.14.3 - Wave Attenuation and Dispersion Measured in the Field 55
1.15 - Separation of two waves from a blast 55
1.16 - Sonic velocities and densities of different mediums 56
1.17 - Concluding remarks 57
1.17.1 - Velocities of P- and S-Waves 57
1.17.2 - Velocities of Body and Surface Waves 59
1.17.3 - Stress Waves and Shock Waves 59
1.17.4 - Stress Wave Reflection from a Free Surface 59
1.17.5 - Reflection and Transmission of Stress Waves Through an Interface 59
1.17.6 - Stresses in One-Dimensional Elastic Waves 60
1.17.7 - Impact of Two Elastic Bars 60
1.17.8 - Elastic Waves Propagating in Two Bars 60
1.17.9 - Elastic Waves to a Rigid Wall and a Free Surface 60
1.17.10 - Spalling Induced by Tensile Stress Waves 60
1.17.11 - Attenuation and Dispersion of Stress Waves in Rocks 60
1.18 - Exercises 60
References 61
Chapter 2 - Shock Waves 62
2.1 - Characteristics of shock waves 62
2.2 - Rankine–Hugoniot jump equations 63
2.2.1 - Developing Rankine–Hugoniot Jump Equations 63
2.2.1.1 - Equation of Mass Conservation 63
2.2.1.2 - Equation of Momentum Conservation 64
2.2.1.3 - Equation of Energy Conservation 64
2.2.2 - Solution to the Rankine–Hugoniot Jump Equations 65
2.2.2.1 - The U?u Hugoniot Equation 65
2.2.2.2 - The p?u Hugoniot Equation 65
2.2.2.3 - The p?v Hugoniot Equation 65
2.2.2.4 - Solution as Equation of State is Known 68
2.2.2.5 - Solving a Shock Wave Problem Based on a Known ?? Hugoniot 68
2.2.2.6 - Solving a Shock Wave Problem Based on a Given Equation of State 69
2.3 - Interaction of shock waves 73
2.3.1 - Impact of Two Different Materials 73
2.3.1.1 - Rankine–Hugoniot Jump Conditions 74
2.3.1.2 - Hugoniot Equations 76
2.3.2 - Impact Between Same Materials 77
2.3.3 - Shock Propagation from One Material to Another 79
2.3.3.1 - Solution to Case 1—ZA <  ZB
2.3.3.2 - Example for Case 1 80
2.3.3.3 - Solution to Case 2—ZA >  ZB
2.3.3.4 - Example for Case 2 81
2.3.4 - Collision of Two Shock Waves 82
2.4 - Rarefaction waves 84
2.5 - Shock wave attenuation 84
2.5.1 - Shock Wave Attenuation Due to Rarefaction 84
2.5.2 - Experimental Result for Shock Wave Attenuation in Different Materials 85
2.5.3 - Shock Wave Attenuation in Rock Blasting 87
2.6 - On applications of shock wave theory 87
2.6.1 - Shock Wave Traveling from Low Impedance Material to High Impedance Material 87
2.6.2 - Shock Wave Traveling from High Impedance Material to Low Impedance Material 87
2.6.3 - Shock Wave Traveling from One Material to a Free Surface 87
2.6.4 - Shock Wave Collision 87
2.7 - Concluding remarks 88
2.7.1 - Rankine–Hugoniot Jump Equations 88
2.7.2 - Hugoniot Relations 88
2.7.3 - p–u Hugoniot Equations 88
2.7.4 - Rarefaction 88
2.7.5 - Shock Wave Propagates from One Material to Another 88
2.7.6 - Shock Wave Reflection on a Free Surface 88
2.7.7 - Shock Wave Collision 88
2.7.8 - Shock Wave Attenuation 89
2.8 - Exercises 89
References 89
Part II - Rock Fracture and Fragmentation 90
Chapter 3 - Rock Fracture and Rock Strength 92
3.1 - Rocks 92
3.1.1 - Igneous Rock 93
3.1.2 - Metamorphic Rock 93
3.1.3 - Sedimentary Rock 94
3.1.4 - Fundamental Characteristics of Rocks 94
3.1.4.1 - A Compound of Multi-Mineral Grains 94
3.1.4.2 - Grain Boundaries 94
3.1.4.3 - Discontinuity 95
3.1.4.4 - Porosity 95
3.1.4.5 - Brittleness 95
3.2 - Geological structures 95
3.2.1 - Effect of Geological Structures on Rock Fracture 95
3.2.2 - Moving Geological Structures 96
3.3 - Rock strength 97
3.3.1 - Definition of Rock Strength 97
3.3.2 - Stress Concentration 98
3.3.3 - Intrinsic Cracks in a Material 99
3.3.4 - Theoretical Strength of Material 100
3.3.5 - Griffith Strength Relation 100
3.3.6 - Griffith Energy-Balance Concept 101
3.4 - Rock fracture and fracture toughness 101
3.4.1 - Fracture Toughness and Energy 101
3.4.2 - Stress Intensity Factor 102
3.4.3 - Rock Fracture in Engineering 103
3.5 - Rock fragmentation 103
3.6 - Relation between rock strengths 103
3.7 - Relation between fracture toughness and strength 104
3.7.1 - Relation Between Mode I Fracture Toughness and Tensile Strength of Rock 104
3.7.2 - Other Relations 105
3.8 - The reason why rock fracture toughness and rock strengths are related 105
3.9 - Process of rock fracture 105
3.9.1 - Link-up of Micro-Cracks 105
3.9.2 - Crack Extension 106
3.9.3 - Tensile or Shear Fracture 106
3.9.4 - Patterns of Rock Fracture in Compressive Strength Tests 106
3.10 - Energy required for rock fracture 106
3.10.1 - Energy Required for Fracture 106
3.10.2 - Energy Expenditure in Rock Fracture 107
3.11 - Discussion 107
3.11.1 - Evaluation of Rock Quality 107
3.11.2 - Mechanism of Rock Failure 107
3.11.3 - Energy Consumed in Rock Fracture 107
3.12 - Concluding remarks 108
3.12.1 - Characteristics of Three Types of Rocks 108
3.12.2 - Factors Affecting Rock Properties 108
3.12.3 - Basic Characteristics of Rocks 108
3.12.4 - Discontinuities of Rock 108
3.12.5 - Geological Structures 108
3.12.6 - Strength and Theoretical Strength 108
3.12.7 - Relation Between Different Rock Strengths 108
3.12.8 - Rock Strength 109
3.12.9 - Relation Between the Strength and Mode I Fracture Toughness of Rock 109
3.12.10 - Fracture Toughness and Fracture Energy 109
3.12.11 - Tensile Fracture in Micro-Scale During Compressive Testing 109
3.12.12 - Tensile Strength 109
3.12.13 - Energy Partitioning in Rock Fracture 109
3.12.14 - Characteristic Impedance of Rock 109
3.12.15 - Difference Between the Effective Fracture Surface Energy and the Energy Actually Consumed 110
3.13 - Exercises 110
References 110
Chapter 4 - Effect of Loading Rate on Rock Fracture 112
4.1 - Loading rate 113
4.1.1 - Definition of Loading Rate 113
4.1.2 - Static, Quasistatic, and Dynamic Loading 113
4.1.3 - Estimated Loading Rate in Rock Boring and Percussive Drilling 113
4.1.4 - How to Change Loading Rate 114
4.2 - Effect of loading rate on Young’s modulus 114
4.3 - Effect of loading rate on compressive rock strength 115
4.4 - Effect of loading rate on tensile rock strength 115
4.5 - Effect of loading rate on shear strength 116
4.6 - Effect of loading rate on rock fracture toughness 117
4.6.1 - Method for Measuring Fracture Toughness 117
4.6.2 - Fracture Toughness of Rock 117
4.6.3 - Effect of Loading Rate on Fracture Toughness of Other Brittle Materials 119
4.7 - Effect of loading rate on sizes of fragments 119
4.7.1 - Fragments From Compressive Strength Tests 119
4.7.2 - Fragments From Tensile Strength Tests 119
4.7.3 - Fragments From Fracture Toughness Tests 119
4.8 - Effect of loading rate on fracture surface characteristics 124
4.8.1 - Characteristics on Fracture Surfaces 124
4.8.2 - Characteristics on Vertical Sections of Fracture Surfaces 124
4.8.3 - Fractal Dimensions of Rock Fracture Surfaces 125
4.9 - Effect of loading rate on energy consumption in rock fracture 125
4.9.1 - Energy Partitioning in Rock Fracture and Compressive Tests 125
4.9.2 - Kinetic Energy in Rock Fracture 127
4.9.3 - Rotation Energy 127
4.9.4 - Experiments on Single-Particle Breakage and Energy Efficiency 128
4.9.5 - Energy Efficiency in Rock Fragmentation 129
4.10 - Engineering applications 129
4.11 - Concluding remarks 130
4.11.1 - Effects of Loading Rate on Rock Strengths and Fracture Toughness 130
4.11.2 - Effects of Loading Rate on Energy Partitioning and Efficiency 130
4.11.3 - Kinetic Energy of Fragments and Its Utilization in Rock Fracture and Fragmentation 131
4.11.4 - Reasons for the Loading Rate Effect on Rock Fracture Toughness 131
4.12 - Exercises 131
References 132
Chapter 5 - Effect of Temperature on Rock Fracture 134
5.1 - Thermal, physical, and mechanical properties of rock 135
5.1.1 - Thermal Properties of Rock 135
5.1.1.1 - Melting Temperature 135
5.1.1.2 - Specific Heat 135
5.1.1.3 - Thermal Conductivity 135
5.1.1.4 - Thermal Diffusivity 135
5.1.2 - Mechanical Properties of Rock 136
5.1.2.1 - Young’s Modulus 136
5.1.2.2 - Poisson’s Ratio 136
5.1.2.3 - Viscosity and Permeability 136
5.1.2.4 - Thermal Expansion 136
5.1.2.5 - Porosity 137
5.1.2.6 - P-Wave Velocity 137
5.1.3 - Thermal Stresses 137
5.2 - Compressive rock strength 137
5.2.1 - Compressive Strength Under Static Loading 137
5.2.1.1 - Heat-Treated Rocks 137
5.2.1.2 - Heating or Cooling Rate 138
5.2.1.3 - Strain Rate 138
5.2.1.4 - Heating Condition 139
5.2.1.5 - Low Temperature (< 0°C)
5.2.2 - Compressive Strength Under Dynamic Loading 140
5.3 - Tensile strength 140
5.3.1 - Heat-Treated Rock 140
5.3.2 - Low Temperature 140
5.4 - Fracture toughness 140
5.4.1 - Fracture Toughness Under Static Loading 140
5.4.1.1 - High Temperature 141
5.4.1.2 - Subzero and Room Temperature 141
5.4.1.3 - High Temperature With Confining Pressure 141
5.4.2 - Dynamic Fracture Toughness 142
5.4.2.1 - Fracture Toughness 142
5.4.2.2 - Breakage of Rock Specimens 142
5.4.2.3 - Characteristics of Crack Branching 142
5.4.3 - Energy Partitioning During Dynamic Fracture 144
5.4.3.1 - Energy Expenditure and Energy Efficiency From Dynamic Fracture Tests 144
5.4.3.2 - Energy Consumption During Static and Dynamic Compression Tests 145
5.5 - Characteristics of thermal damage 145
5.5.1 - Characteristics of Fracture 145
5.5.2 - Thermal Damage 148
5.5.2.1 - Thermal Cracking in Grain Boundaries and Within Grains 148
5.5.2.2 - Reasons for Thermal Damage 148
5.5.3 - Fracture Energy and Thermal Damage 149
5.6 - Rock fragmentation 149
5.6.1 - Thermally Assisted Liberation in Comminution 149
5.6.2 - Thermally Assisted Liberation in Secondary Metal Recovery 149
5.6.3 - Water and Thermal Spalling 149
5.7 - Cyclic temperature loading to rock 149
5.8 - Dynamic fracture mechanism of rock 150
5.9 - On applications 151
5.9.1 - Using High Temperature Combined With Low Loading Rate to Fracture Rock 151
5.9.2 - Improving Efficiency of Size Reduction Processes 151
5.9.3 - Microwave Radiation 151
5.9.4 - Thermal Mechanical Drilling and Tunneling 151
5.9.5 - Thermal Fracture of Stones 152
5.9.6 - Thermal Rock-Weakening Techniques 152
5.9.7 - Challenges in Rock Drilling, Boring, and Blasting due to High Temperature 152
5.10 - Concluding remarks 153
5.10.1 - Rock Properties 153
5.10.2 - Effect of High Temperature on Rock Strengths 154
5.10.3 - Effect of Heating or Cooling Rate and Heating Methods on Rock Fracture 154
5.10.4 - Effect of High Temperature on Rock Fracture Toughness 154
5.10.5 - Thermal Damage Caused by Heat Treatment 154
5.10.6 - Applications 154
5.11 - Exercises 154
References 155
Chapter 6 - Environmental Effects on Rock Fracture 158
6.1 - Water 158
6.1.1 - Water Saturation With Time 159
6.1.2 - Effective Pressure 159
6.1.3 - Effect of Water Saturation on Elastic Wave Velocity and Rock Fracture 160
6.1.4 - Effect of Water on Rock Strength and Fracture Toughness 160
6.1.5 - Effect of Water on the Stability of Tunnels and Slopes 162
6.1.6 - Water Effect and Loading Rate 163
6.1.7 - Effect of Water on Grinding 163
6.1.8 - Effect of Water on Blasting 163
6.2 - Chemical liquids 164
6.2.1 - Effect of Chemical Liquids on Compressive Strength 164
6.2.2 - Effect of Chemical Liquids on Tensile Strength of Limestone 164
6.2.3 - Effect of Chemical Liquids on Fracture Toughness 164
6.3 - Confining pressure 164
6.3.1 - Effect of Confining Pressure on Wave Velocity and Wave Attenuation 165
6.3.2 - Effect of Confining Pressure on Young’s Modulus and Poisson’s Ratio 167
6.3.3 - Effect of Confining Pressure on Compressive Strength 167
6.3.4 - Effect of Confining Pressure on Fracture Toughness 168
6.3.5 - Effect of Confining Pressure on the Stability of Tunnel 168
6.4 - Cyclic loading 171
6.4.1 - Fatigue Strength of Rock 171
6.4.2 - Effect of Cyclic Number on Fatigue Strength 173
6.4.3 - Effect of Cyclic Amplitude on Fatigue Strength 173
6.4.4 - Effect of Cyclic Frequency on Fatigue Strength 173
6.4.5 - Fatigue Strength of Saturated, Frozen, and Jointed Rock 173
6.5 - Concluding remarks 174
6.5.1 - Effect of Water on Rock Fracture 174
6.5.2 - Effect of Chemical Fluids on Rock Fracture 174
6.5.3 - Effect of Confining Pressure on Rock Fracture 174
6.5.4 - Effect of Cyclic Loading on Rock Fracture 174
6.6 - Exercises 175
References 175
Chapter 7 - Rock Drilling and Boring 178
7.1 - Methods for rock drilling and boring 178
7.1.1 - Percussive Drilling 178
7.1.2 - Rotary Drilling 180
7.1.3 - Rock Boring 182
7.2 - Mechanism of rock breakage 184
7.2.1 - Indenters 184
7.2.2 - Elastic Stress Distribution 184
7.2.3 - Elastic–Plastic Indentation 187
7.2.4 - Crack Length and Penetration 188
7.2.5 - Mechanisms of Rock Drilling 190
7.3 - Loading rate AND temperature 191
7.3.1 - Loading Rate 191
7.3.2 - Temperature 191
7.4 - Discharge of cuttings during drilling and boring 192
7.4.1 - Effect of Cutting Discharge on the Speed of Drilling and Boring 192
7.4.2 - Methods for Discharging Cuttings 192
7.5 - Deviation 192
7.6 - Operational skills 192
7.6.1 - Choosing Drilling Methods and Drill Hole Sizes 192
7.6.2 - Drilling Speed and Drill Bit Reshaping 193
7.6.3 - Correct Operation 193
7.7 - Potential to development 193
7.7.1 - Rock Boring 193
7.7.2 - Percussive Drilling 194
7.7.3 - Rotary Drilling 195
7.8 - Concluding remarks 195
7.8.1 - Percussive Drilling 195
7.8.2 - Rotary Drilling 196
7.8.3 - Rock Boring 196
7.8.4 - Potential Development of Rock Drilling and Boring 196
7.9 - Exercises 196
Appendix I 197
References 198
Part III - Explosive Donation in a Blast Hole 200
Chapter 8 - Explosives and Detonators 202
8.1 - History 202
8.2 - Categories of explosives 203
8.2.1 - Primary Explosives 203
8.2.2 - Secondary Explosives 203
8.2.3 - Tertiary Explosives 203
8.2.4 - Ammonium Nitrate 203
8.2.5 - Water Gels or Slurries 203
8.2.6 - Dynamite 204
8.2.7 - Explosives in Underground Coal Mining 204
8.3 - ANFO explosives 204
8.4 - Emulsion explosives 204
8.5 - ANFO–emulsion mixtures, low-density explosives, and propellants 205
8.5.1 - ANFO–Emulsion Mixtures 205
8.5.2 - Low-Density Explosives 205
8.5.3 - Propellants 205
8.6 - Initiation of explosives 205
8.6.1 - Explosion and Oxygen Balance 205
8.6.2 - Connection Between Detonators and Detonating Cord 205
8.6.3 - Charging Operation 207
8.6.4 - Sympathetic Detonation 207
8.6.5 - Desensitization 208
8.6.6 - Deflagration 208
8.7 - Detonators 208
8.7.1 - Electric Detonators 209
8.7.2 - Nonelectric Detonators 209
8.7.3 - Electronic Detonator 209
8.7.4 - Detonating Cord 210
8.8 - Precision in the initiation of detonators 210
8.9 - Charge diameter and VOD 211
8.9.1 - VOD of ANFO and Emulsions 211
8.9.2 - Energy Loss 211
8.9.3 - Critical Diameter 213
8.10 - Matching of explosives and rock mass 213
8.10.1 - Case 1—?? 213
8.10.2 - Case 2—?? 213
8.10.3 - VOD and Fragmentation 215
8.11 - Safety in charging operation 215
8.12 - On the relation between VOD and rock fracture 216
8.13 - Concluding remarks 216
8.13.1 - Oxygen Balance and Explosive Energy 216
8.13.2 - ANFO Explosives 216
8.13.3 - Emulsion Explosives 216
8.13.4 - Heavy ANFO 217
8.13.5 - Electric Detonators 217
8.13.6 - Nonelectric Detonators 217
8.13.7 - Electronic Detonators 217
8.13.8 - Precision of Initiation 217
8.13.9 - Matching of Explosive and Rock Mass 217
8.14 - Exercises 217
References 218
Chapter 9 - Theory of Detonation 220
9.1 - Introduction 220
9.2 - Definitions 221
9.2.1 - Detonation 221
9.2.2 - Steady Detonation 221
9.2.3 - Ideal and Nonideal Detonation 221
9.2.4 - Entropy 221
9.2.5 - Isentrope 221
9.3 - CJ detonation theory 221
9.3.1 - CJ Model 221
9.3.2 - Solution to the CJ Model 222
9.3.3 - Estimating the CJ Values in Condensed Explosive 223
9.3.4 - Solution to CJ Theory 224
9.3.5 - Example for Pressure Estimate 224
9.4 - ZND theory 225
9.4.1 - ZND Model 225
9.4.2 - Solution to the ZND Model 226
9.4.3 - Limitation of CJ and ZND Theories 229
9.5 - Direct numerical solution 231
9.6 - Two-dimensional detonation theories 232
9.6.1 - A General Description of 2D Nonideal Steady Detonation 232
9.6.2 - Detonation Shock Dynamics 233
9.6.3 - Streamline Approach 233
9.7 - Equation of state 234
9.7.1 - EoS Without Explicit Chemistry 234
9.7.2 - EoS with Explicit Chemistry 234
9.7.3 - Hugoniot for Commercial Explosives and Rocks 234
9.8 - Chemical reaction rate 235
9.9 - Rarefaction waves 236
9.10 - Summary 237
9.10.1 - CJ Theory 237
9.10.2 - ZND Theory 238
9.10.3 - Limitation of CJ and ZND Theories 238
9.10.4 - Direct Numerical Solution 238
9.10.5 - Detonation Shock Dynamics 238
9.10.6 - Streamline Approach 238
9.10.7 - EoS and Chemical Reaction Rate 238
9.10.8 - Rarefaction Waves 238
9.11 - Exercises 238
References 239
Chapter 10 - Single-Hole Blasting 240
10.1 - Process of rock blasting in a single hole 240
10.1.1 - Blast-Caused Fracture Pattern 240
10.1.2 - Blasting Process in a Blasthole 242
10.2 - Borehole pressures 243
10.2.1 - Definitions of Borehole Pressure and Detonation Wave 243
10.2.2 - Borehole Pressure Measured From Block Models 244
10.2.3 - Borehole Pressure From Field Measurements 245
10.2.4 - Summary of Borehole Pressure Measurement 245
10.3 - Stress waves close to boreholes 246
10.4 - Borehole expansion 247
10.5 - Gas velocity 248
10.6 - Crushed zone 248
10.7 - Velocity of crack propagation 248
10.7.1 - Theoretical Prediction 248
10.7.2 - Measurement 249
10.8 - Movement of fragments during blasting 249
10.8.1 - Measurement 249
10.8.2 - Factors Influencing Burden Velocity 249
10.8.2.1 - Charge Weight and Charge Length 249
10.8.2.2 - Burden 250
10.9 - Disturbed zone surrounding a blasthole 251
10.9.1 - Measurements on Fractured Zone 251
10.9.1.1 - Measurements From Decoupled Charge in the Field 252
10.9.2 - Empirical Formulas for Fractured Zone 252
10.10 - Energy distribution 253
10.10.1 - Equation of Energy Distribution 253
10.10.2 - Determination of Each Form of Energy 253
10.10.2.1 - Fragmentation Energy 253
10.10.2.2 - Seismic Energy 253
10.10.2.3 - Kinetic Energy 254
10.10.2.4 - Rotation Energy ER 254
10.10.2.5 - Energy Carried by Gases Escaping from Stemming 254
10.10.2.6 - Internal Fracturing Energy 254
10.10.2.7 - Other Forms of Energy 255
10.10.3 - Measurement of Each Form of Energy 255
10.10.3.1 - Fragmentation Energy, Seismic Energy, and Kinetic Energy 255
10.10.3.2 - Energy Carried Away by Gas Escaping Through Collar 255
10.10.3.3 - Internal Fracturing Energy 255
10.10.3.4 - Seismic Energy and Rock Confinement 255
10.11 - Concluding remarks 256
10.11.1 - Detonation Wave and Borehole Pressure 256
10.11.2 - Blast-Caused Borehole Expansion, Crushed Zone, and Fractured Zone 256
10.11.3 - Crack Velocity in Rock 256
10.11.4 - Velocity of Burden or Fragments 256
10.11.5 - Fractured Zone 256
10.11.6 - Energy Distribution in Blasting 257
10.12 - Exercises 257
References 257
Part IV - Basic Parameters of Rock Blasting 260
Chapter 11 - Free Surface and Swelling in Blasting 262
11.1 - Weakness of rock materials 262
11.2 - Role of free surface 262
11.2.1 - Source of Tensile Stresses 262
11.2.2 - Increase in Energy Efficiency 263
11.2.3 - Reduction of Ground Vibrations 263
11.3 - Dynamic tensile fracture—spalling in rock blasting 263
11.3.1 - Principle of Spalling 263
11.3.2 - Spalling Close to Free Surface Due to Blasting 263
11.4 - Spalling in the free surface far from explosive charge 268
11.4.1 - First Blast 268
11.4.2 - Second Blast 269
11.4.3 - Third Blast 270
11.4.4 - Spalling in the Top of Drift 271
11.4.5 - Summary on Spalling 271
11.5 - Swelling in blasting 273
11.5.1 - Case 1—Natural Swelling 273
11.5.2 - Case 2—A Limited Space for Swelling 273
11.5.3 - Case 3—A Small Swelling Space 273
11.5.4 - Case 4—Dynamic Swelling Space 274
11.6 - Creation of free surface and swelling space by blasting 275
11.7 - On applications 276
11.8 - Concluding remarks 276
11.8.1 - Free Surface in Rock Blasting 276
11.8.2 - Geometrical Shape of a Free Surface 277
11.8.3 - Free Surface and Rock Support 277
11.8.4 - Swelling Space 277
11.9 - Exercises 277
References 277
Chapter 12 - Burden and Spacing 278
12.1 - Angle of breakage 278
12.2 - Specific charge 280
12.2.1 - Definition of Specific Charge 280
12.2.2 - Actual Stress and Energy Distribution 280
12.2.2.1 - Initiation Position 280
12.2.2.2 - Quantity of Initiation Positions 280
12.2.2.3 - Stemming 281
12.2.2.4 - Delay Time and Initiation Accuracy 281
12.2.2.5 - Misfire 281
12.2.2.6 - Coupled and Decoupled Charge 282
12.2.2.7 - Drilling Plan 282
12.2.3 - Determining the Specific Charge 282
12.3 - Diameter of blastholes 282
12.3.1 - Velocity of Detonation (VOD) 282
12.3.2 - Quality of Rock Drilling 283
12.3.3 - Production and Productivity 283
12.3.4 - Fragmentation 283
12.3.5 - Cost of Development 283
12.3.6 - Back Break 283
12.3.7 - Ground Vibrations 284
12.3.8 - Determining the Diameter of Blasthole 284
12.4 - Burden 284
12.4.1 - Factors Related to Burden 284
12.4.1.1 - Diameter of Blasthole 284
12.4.1.2 - Decoupled Charge 284
12.4.1.3 - Rock Properties 284
12.4.1.4 - Explosive 284
12.4.1.5 - Specific Charge 285
12.4.1.6 - Wave Attenuation 285
12.4.1.7 - Fragmentation 285
12.4.1.8 - Production and Productivity 285
12.4.1.9 - Vibrations 285
12.4.2 - Determining the Burden 285
12.4.2.1 - Empirical Method 285
12.4.2.2 - Determining the Burden in Surface Control 285
12.4.2.3 - Determining the Burden in Production Blasting 286
12.5 - Spacing 288
12.5.1 - Relation Between Burden and Spacing in Ordinary Blasting 288
12.5.1.1 - Case S> B
12.5.1.2 - Case S?B 289
12.5.2 - Relation Between Burden and Spacing in Smooth Blasting 291
12.6 - Concluding remarks 291
12.6.1 - Angle of Breakage 291
12.6.2 - Specific Charge 291
12.6.3 - Diameter of Blasthole 292
12.6.4 - Burden 292
12.6.5 - Spacing 292
12.7 - Exercises 292
References 292
Chapter 13 - Stemming and Charge Length 294
13.1 - Effect of stemming on detonation wave and energy 294
13.1.1 - Energy Loss From Collar and Stemming 294
13.1.2 - Reflection-Induced Variation of Detonation Wave 295
13.2 - Role of stemming in blasting 297
13.2.1 - To Avoid or Reduce Energy Loss 297
13.2.1.1 - Analysis 297
13.2.1.2 - Confirmation From Measurements 297
13.2.2 - To Keep Explosive in Blastholes 298
13.2.3 - To Reduce Fly Rock and Air Blast 298
13.2.4 - To Reinforce Borehole Pressure by Using Better Stemming Materials 298
13.2.5 - To Increase Crack Density and Crack Length 298
13.2.6 - To Consume Some Energy 298
13.3 - Example of improved fragmentation by better stemming 299
13.4 - Determining the sizes and material of stemming 299
13.4.1 - Case A—One Primer Placed Close to the Collar 300
13.4.2 - Case B—One Primer Placed at the Middle of Charged Hole 300
13.4.3 - Case C—One Primer Placed at the Bottom of Charged Hole 300
13.5 - Charge length 301
13.6 - Concluding remarks 302
13.6.1 - Effect of Stemming on Detonation Energy 302
13.6.2 - Effect of Stemming on Detonation Wave and Rock Fracture 302
13.6.3 - Functions of Stemming 303
13.6.4 - How to Choose Correct Stemming 303
13.6.5 - Necessity of Stemming 303
13.6.6 - Charge Length 303
13.7 - Exercises 303
References 304
Chapter 14 - Air Deck and Smooth Blasting 306
14.1 - Air deck 306
14.1.1 - Background 306
14.1.2 - Laboratory Experiments 306
14.1.3 - Parameters of Air Deck Charge 308
14.1.4 - Results From Industrial Applications 308
14.1.5 - Recommendation for Air Deck Charge 309
14.2 - Decoupled charge 309
14.2.1 - Definition of Decoupling and Coupling 309
14.2.2 - Mechanism of Decoupled Charge 310
14.2.3 - Mechanism of Decoupled Charge With Liquid or Solid Materials 310
14.2.4 - Effect of Decoupling Ratio on Fragmentation 311
14.2.5 - Application of Decoupled Charge 312
14.2.6 - Air Cavity Charge 312
14.3 - Deck charge 313
14.3.1 - Principles of Deck Charge 313
14.3.2 - Shock Wave Attenuation in Stemming 314
14.4 - Principles of smooth blasting and presplit technique 315
14.4.1 - Stress Analysis 315
14.4.2 - Experiments 316
14.5 - Smooth blasting 316
14.5.1 - Burden and Spacing 316
14.5.2 - Factors Influencing Quality of Smooth Blasting 317
14.5.3 - Result From Smooth Blasting 317
14.6 - Presplit blasting 318
14.6.1 - Spacing 318
14.6.2 - Examples from Rock Engineering 318
14.7 - Special methods in smooth and presplit blasting 318
14.8 - Concluding remarks 319
14.8.1 - Air Deck Technique 319
14.8.2 - Decoupled Charge 319
14.8.3 - Deck Charge 319
14.8.4 - Smooth Blasting 319
14.8.5 - Crack Velocity and Stress Superposition 319
14.8.6 - Presplit Technique 319
14.9 - Exercises 320
References 320
Chapter 15 - Primer Placement 322
15.1 - Wastage of detonation energy 322
15.1.1 - Single-Primer Placement 322
15.1.1.1 - Primer Close to Collar 322
15.1.1.2 - Primer at Middle of Charge 323
15.1.1.3 - Primer Between Middle and Bottom of Charged Hole 323
15.1.2 - Double-Primer Placement 323
15.2 - Primer position and misfires 324
15.2.1 - The Reason for Misfires 325
15.2.2 - Field Measurements of Misfires in Sublevel Caving 326
15.3 - Stress wave propagation and stress distribution 326
15.3.1 - Single-Primer Placement 326
15.3.2 - Double-Primer Placement 328
15.3.2.1 - Shock Wave Collision 328
15.3.2.2 - Stress Distribution 328
15.4 - Amplitude of stresses in rock 330
15.5 - Rock fragmentation 330
15.5.1 - Fragmentation From Single-Primer Placement 331
15.5.2 - Fragmentation From Double-Primer Placement 331
15.6 - Ore extraction 331
15.6.1 - Single-Primer Placement 331
15.6.2 - Double-Primer Placement 332
15.7 - Productivity 334
15.7.1 - Relation Between Ore Extraction and Fragmentation 334
15.7.2 - Relation Between Ore Extraction and Iron Content 334
15.8 - Mining safety relevant to brow damage 334
15.8.1 - Single-Primer Placement 334
15.8.2 - Double-Primer Placement 335
15.9 - Potential economy of improving blasting 335
15.10 - On double-primer placement 335
15.11 - Concluding remarks 335
15.12 - Exercises 336
References 337
Chapter 16 - Delay Times 338
16.1 - Reasons for a delay time 338
16.1.1 - Ground Vibrations 338
16.1.2 - Rock Damage Nearby 340
16.1.3 - Seismic Events 340
16.1.4 - Rock Fragmentation 340
16.2 - Factors to be considered in determining delay time 340
16.2.1 - Stress Distribution 340
16.2.2 - Crack Propagation 341
16.2.3 - Detonation Waves 341
16.2.4 - Confinement and Boundary Conditions 342
16.2.5 - Rock Fracture Nearby 342
16.2.6 - Vibrations in Far Field 342
16.2.7 - Movement of Fragments 342
16.3 - Delay time in a single blasthole 342
16.3.1 - One Detonator Position 342
16.3.2 - Multidetonator Positions 344
16.3.2.1 Same Delay Time 344
16.3.2.2 Different Delay Times 344
16.4 - Delay time between two adjacent blastholes 344
16.4.1 - Background 344
16.4.2 - Fragmentation Radius Rfg Smaller Than Spacing S 345
16.4.3 - Fragmentation Radius Rfg Equal to or Larger Than Spacing S 349
16.5 - Delay time between adjacent rows 350
16.5.1 - Stress Wave Superposition 350
16.5.2 - Collision of Fragments 350
16.5.2.1 Collision Between Fragments From Multirows in Open Pit Blasting 350
16.5.2.2 Collision of Fragments in Sublevel Caving 351
16.6 - Simultaneous initiation in production blasts 351
16.6.1 - Stress Analysis 352
16.6.2 - Test Results 352
16.7 - Comments on delay time 353
16.8 - Concluding remarks 353
16.8.1 - Reasons for a Delay Time and Factors Affecting Delay Time 353
16.8.2 - Delay Time in a Single Hole 353
16.8.3 - Stress Distribution and Delay Time 353
16.8.4 - Simultaneous Blasting 354
16.9 - Exercises 354
References 354
Part V - Rock Blasting in Engineering 356
Chapter 17 - Rock Blasting in Open Cut and Tunneling 358
17.1 - Introduction 358
17.2 - Open cut blasting in underground mining 359
17.2.1 - Effect of Open Cut on Mining Production 359
17.2.2 - Cut Blasting Methods in Underground Mining 359
17.2.2.1 - Raise Boring 360
17.2.2.2 - Slot Drilling 363
17.3 - Cut Blasting in Drifting and Tunneling 366
17.3.1 - Cut Blasting With Two Uncharged Holes 367
17.3.2 - Other Methods for Cut Blasting 367
17.4 - Detonators and Delay Time 369
17.4.1 - Delay Time 369
17.4.2 - Detonators 369
17.5 - Slashing hole blasting 369
17.5.1 - Burden 369
17.5.2 - Delay Time 369
17.5.3 - Initiation Sequence 370
17.6 - Disturbed zone 370
17.6.1 - Influence of Disturbed Zone on Drift Stability and Safety 370
17.6.2 - Influence of Disturbed Zone on Rock Support 370
17.6.3 - Factors Influencing Disturbed Zone 370
17.7 - Blastholes in roofs and walls 371
17.7.1 - Charge and Burden 371
17.7.2 - Delay Time and Initiation 372
17.8 - Bottom and slashing holes 373
17.9 - Quality, safety, and economy 373
17.9.1 - Cut Blasting 373
17.9.2 - In Situ Stress Field 373
17.9.3 - Decoupled Charge 373
17.10 - Concluding remarks 374
17.10.1 - Open Cut Blasting 374
17.10.2 - Cut Blasting in Tunneling 375
17.10.3 - Disturbed Zone and Decoupled Charge 375
17.11 - Exercises 375
References 376
Chapter 18 - Rock Blasting in Open Pit Mining 378
18.1 - Drilling plan 378
18.1.1 - Burden and Spacing 378
18.1.2 - Subdrilling 379
18.1.2.1 - Role of Subdrilling 379
18.1.2.2 - Length of Subdrilling 380
18.1.3 - Inclination of Bench 380
18.1.3.1 - Back Break 380
18.1.3.2 - Production Volume 381
18.1.3.3 - Fragmentation Close to Bench Floor 381
18.2 - Blast plan 381
18.2.1 - Stemming 382
18.2.2 - Deck Charge and Air Deck 382
18.2.2.1 - Deck Charge 382
18.2.2.2 - Air Deck 382
18.2.3 - Primers 383
18.2.3.1 - Single Primer in Each Borehole 383
18.2.3.2 - Two Primers in Each Borehole 384
18.2.3.3 - Multiple-Primer Positions in Each Borehole 385
18.2.4 - Initiation and Delay Time 385
18.2.4.1 - Reasons for a Delay Time 385
18.2.4.2 - Choosing a Delay Time Between Holes and Between Rows 385
18.2.4.3 - Initiation Sequence 386
18.3 - Fragmentation 386
18.3.1 - Stress Superposition 386
18.3.1.1 - Pyrotechnic or Nonelectronic Detonators 386
18.3.1.2 - Electronic Detonators 386
18.3.2 - Shock Wave Collision 386
18.3.3 - Barrier to Free Face 387
18.3.3.1 - Principles of Barrier to Free Face 387
18.3.3.2 - Measures for Making a Barrier to Free Face 388
18.3.4 - Increase in Specific Charge 389
18.4 - Final pit slope 389
18.4.1 - Slope Angle and Mining Cost 389
18.4.2 - Quality and Stability of Slope 389
18.5 - Safety and environment 390
18.5.1 - Collapse of Slopes 390
18.5.2 - Fly Rocks and Air Blasts 390
18.5.2.1 - Insufficient Stemming 390
18.5.2.2 - Loose Rock or Discontinuity in Rock Mass 391
18.5.2.3 - Top Initiation 391
18.5.2.4 - High Specific Charge 391
18.5.3 - Ground Vibrations 392
18.6 - On presplit method and production blasting 392
18.7 - Concluding remarks 392
18.7.1 - Subdrilling 392
18.7.2 - Inclination of Bench 393
18.7.3 - Stemming 393
18.7.4 - Deck Charge and Air Deck 393
18.7.5 - Primer Placement 393
18.7.6 - Fragmentation 393
18.7.7 - Stability of Open Pit Slopes 393
18.7.8 - Fly Rock and Air Blast 393
18.8 - Exercises 393
References 394
Chapter 19 - Rock Blasting in Underground Mining 396
19.1 - Advantages and disadvantages of sublevel caving 396
19.2 - Drilling and charging plan 397
19.2.1 - Burden and Spacing 397
19.2.1.1 - Burden 397
19.2.1.2 - Spacing 397
19.2.2 - Length of Blastholes 398
19.2.2.1 - Large Ore Body 398
19.2.2.2 - Narrow Ore Body 399
19.2.3 - Uncharged Length 400
19.2.3.1 - As Delay Time Is Longer Than Fragmentation Time 400
19.2.3.2 - As Delay Time Is Shorter Than Fragmentation Time 400
19.2.4 - Precision of Rock Drilling 400
19.3 - Inclination of rings 400
19.3.1 - Loading and Ore Flow 400
19.3.2 - Brow Protection 402
19.4 - Single- or multiple-ring blasting 403
19.4.1 - Single-Ring Blasting 403
19.4.2 - Double-Ring Blasting 404
19.5 - Delay time and initiation sequence 405
19.5.1 - Delay Time 405
19.5.2 - Initiation Sequence 405
19.5.3 - Initiation and Delay Time in Special Cases 405
19.6 - Open cut and drifting 406
19.7 - Stemming, air deck, and detonator placement 406
19.8 - Back break and brow damage 407
19.8.1 - Back Break 407
19.8.2 - Brow Damage 408
19.8.2.1 - Consequences Caused by Brow Damage 408
19.8.2.2 - Factors Influencing Brow Damage 408
19.8.2.3 - Measures for Reducing Brow Damage 408
19.9 - Misfires 410
19.10 - Fragmentation, ore recovery, and mining profit 410
19.11 - Safety, environment, and vibration control 411
19.11.1 - Safety 411
19.11.2 - Environment 411
19.11.3 - Ground Vibrations 412
19.12 - Sublevel-caving blasting in the future 412
19.13 - Concluding remarks 413
19.13.1 - Characteristics of Sublevel Caving Blasting 413
19.13.2 - Subdrilling, Deviation, and Inclination 413
19.13.3 - Single-Ring Blasting and Double-Ring Blasting 414
19.13.4 - Delay Time 414
19.13.5 - Brow Damage 414
19.13.6 - Misfire 414
19.13.7 - Other Issues Related to Sublevel Caving Blasting 414
19.13.8 - Underground Blasting in the Future 414
19.14 - Exercises 414
References 415
Chapter 20 - Numerical Simulation of Rock Blasting 416
20.1 - Fracture characteristics of rock 416
20.1.1 - Characteristics of Rock Material 416
20.1.1.1 - Composition 416
20.1.1.2 - Boundary and Porosity 416
20.1.1.3 - Intergranular and Intragranular Fracture 417
20.1.1.4 - Geological Structures 417
20.1.2 - Characteristics of Rock Fracture 418
20.1.2.1 - Attenuation 418
20.1.2.2 - Fracture Mode 418
20.1.2.3 - Loading Rate Effect 418
20.1.2.4 - Confining Pressure Effect 418
20.1.2.5 - Fatigue Strength 418
20.1.2.6 - Fluid or Water Effect 418
20.2 - Process of rock blasting in a blasthole 419
20.2.1 - Detonation Waves at Different Positions 419
20.2.2 - Detonation Waves and Gases 420
20.3 - Crushing, fracture, and fragmentation 420
20.3.1 - Crushed Zone 420
20.3.2 - Rock Fracture 421
20.3.3 - Rock Fragmentation 421
20.4 - Shock wave collision 422
20.5 - Stemming 422
20.6 - Malfunction or misfire 423
20.7 - Numerical simulation of detonation 423
20.7.1 - Ideal Detonation 423
20.7.2 - Nonideal Detonation 423
20.7.3 - Equations of State for Detonation Products 424
20.7.3.1 - JWL EoS for Explosive Detonation 424
20.7.3.2 - Williamsburg EoS 424
20.8 - Numerical modeling of rock blasting 425
20.8.1 - Models Used in Rock Fracture 425
20.8.2 - Modeling Rock Fracture by Blasting 425
20.8.3 - Blast Modeling for Whole Process From Detonation to Muckpile 426
20.8.4 - Challenges in Blast Modeling 428
20.9 - Concluding remarks 429
20.10 - Exercises 429
References 429
Part VI - Rock Blasting on Economy, Safety, and Vibrations 432
Chapter 21 - Optimum Fragmentation 434
21.1 - Effects of fragmentation on mining engineering 434
21.1.1 - Effect of Fragmentation on Energy Consumption 434
21.1.2 - Effect of Fragmentation on Ore Recovery 436
21.1.3 - Effect of Fragmentation on Productivity 436
21.1.3.1 - Extraction Speed 436
21.1.3.2 - Mill Throughput 436
21.2 - Factors influencing fragmentation 437
21.2.1 - Explosives 437
21.2.2 - Initiators 437
21.2.3 - Rocks 438
21.2.4 - Drilling Plan 438
21.2.5 - Blast Plan 438
21.3 - Definition of optimum fragmentation 438
21.4 - Possibility of optimum fragmentation 439
21.4.1 - Possibility of Changing Energy Distribution 439
21.4.1.1 - Different Energy Efficiencies 439
21.4.1.2 - Effects of Blast-Induced Cracks on Grinding 439
21.4.2 - To Increase Energy Efficiency in Blasting 441
21.4.3 - To Increase Energy Efficiency in Other Operations 441
21.5 - Measures for optimum fragmentation 441
21.5.1 - Redistribution of Energy Consumption 441
21.5.1.1 - Feasibility of Redistribution of Energy Expenditure 442
21.5.1.2 - Measures for Energy Redistribution 442
21.5.2 - To Increase Explosive Energy in Blasting 442
21.5.3 - To Increase Energy Efficiency in Individual Operations 443
21.5.4 - Ore Recovery, Productivity, Safety, and Environment Control 443
21.6 - Laboratory tests and industry practices on optimum fragmentation 443
21.6.1 - Laboratory Tests 443
21.6.2 - Industry Practices 443
21.7 - How to achieve optimum fragmentation 444
21.7.1 - Step 1—To Make Successful Blasting 444
21.7.2 - Step 2—To Achieve Optimum Fragmentation 444
21.8 - Concluding remarks 444
21.9 - Exercises 445
References 445
Chapter 22 - Effect of Blasting on Engineering Economy 448
22.1 - Introduction 448
22.2 - Ore recovery 448
22.2.1 - Definition 448
22.2.2 - Ore Loss 450
22.2.2.1 - Loss of Natural Resources 450
22.2.2.2 - Increase in Mining Costs 450
22.2.2.3 - Earlier Heavy Investments Such as Developing New Main Levels 451
22.3 - Dilution 452
22.4 - Measures for increasing ore recovery 452
22.4.1 - Scientific Rock Blasting 452
22.4.2 - Optimal Mining Planning 454
22.4.3 - Correct Control of Cutoff Grade 454
22.5 - To increase productivity by blasting 455
22.5.1 - Speed of Ore Extraction 455
22.5.2 - Relation Between Fragmentation and Recovery 456
22.6 - To reduce fractured zone so as to reduce costs in rock support 457
22.7 - Optimization of fragmentation 457
22.8 - Concluding remarks 458
22.8.1 - Direct Economic Loss Due to Ore Loss in Mining 458
22.8.2 - Indirect Economic Losses Due to Ore Loss in Mining 458
22.8.3 - Dilution-Caused Economic Loss 458
22.8.4 - Measures for Increasing Ore Recovery 458
22.8.5 - Effect of Fragmentation on Mining Productivity 458
22.8.6 - Effect of Blasting on Rock Support 458
22.9 - Exercises 458
References 459
Chapter 23 - Safety in Rock Engineering 460
23.1 - Rock spalling 460
23.1.1 - Location of Spalling 460
23.1.2 - Factors Affecting Spalling 461
23.1.3 - Estimate and Reduction of Spalling 462
23.2 - Remained roofs 463
23.2.1 - Common Method for Breaking Down a Remained Roof 463
23.2.2 - New Method for Breaking Down a Remained Roof 464
23.3 - Seismic events 465
23.3.1 - Simplest Principle of Seismic Events 465
23.3.2 - Relation Between Blasting and Seismic Events 466
23.3.3 - Characteristics of Seismic Events in Underground Mining 466
23.3.3.1 - Location of Seismic Events 466
23.3.3.2 - Characteristics of Stresses in Seismic Events 466
23.3.4 - Consequence of Seismic Events 469
23.3.5 - Measures for Reducing Seismic Events 469
23.3.5.1 - To Reduce the Weight of Explosive That Is Initiated Instantaneously 469
23.3.5.2 - Correct Loading Method Under Hanging Wall 470
23.3.5.3 - To Avoid Dynamic Impact by Caved Rock 471
23.4 - Rock fall 472
23.4.1 - Reasons for Rock Fall 472
23.4.2 - Small-Scale Rock Fall 473
23.4.3 - Large-Scale Rock Fall 473
23.4.4 - Measures for Reducing Rock Fall 473
23.5 - Brow damage 474
23.6 - Shock wave damage in underground mines 477
23.6.1 - Shock Wave Damage Caused by Blasting 477
23.6.2 - Measures for Reducing Shock Wave Damage by Blasting 477
23.7 - Slope collapse in open pit mines 478
23.8 - Fly rock and air blast in open pit mines 478
23.9 - Rock burst 478
23.10 - Explosives and detonators 479
23.11 - Concluding remarks 480
23.11.1 - Spalling in Tunnel Surfaces 480
23.11.2 - Remained Roof 480
23.11.3 - Seismic Events 480
23.11.4 - Rock Fall 480
23.11.5 - Brow Damage 480
23.11.6 - Air Shock Damage 480
23.11.7 - Slope Collapse 480
23.11.8 - Fly Rock, Air Blast, and Rock Burst 480
23.12 - Exercises 481
References 481
Chapter 24 - Reduction of Ground Vibrations 482
24.1 - Characteristics of blast-induced ground vibrations 482
24.1.1 - Amplitude of Vibration Waves 483
24.1.2 - Waveform of Vibrations 484
24.1.3 - Technical Ways Toward Vibration Control 484
24.1.4 - Evaluation and Regulations of Ground Vibrations 486
24.2 - To reduce original stress waves caused by blasting 486
24.2.1 - To Choose Smaller Diameter of Borehole 486
24.2.2 - To Choose Smaller Burden 486
24.2.3 - To Choose a Short Blasthole 489
24.2.3.1 - Theoretical Analysis 489
24.2.3.2 - Confirmation From Practical Blasts 490
24.2.4 - To Divide a Single Blast Into Multiple Blasts 490
24.2.4.1 - DSB Method 490
24.2.4.2 - Application in Industry 491
24.2.5 - To Avoid Simultaneous Multihole Initiation at the Beginning of a Blast 492
24.2.6 - To Use Decoupled Charge 493
24.2.7 - To Use Multideck Charge 493
24.2.8 - Other Methods 493
24.3 - To make use of stress wave superposition 493
24.3.1 - Fundamental Principles 493
24.3.2 - Reproducible Waveforms of Single Shots 494
24.3.3 - Applications in Mines 496
24.3.4 - Comments on Wave Superposition Method 496
24.4 - To make ground vibrations damped 496
24.4.1 - Theoretical Background 496
24.4.2 - To Change Initiation Sequence and Reduce Vibrations 498
24.4.3 - Application at Malmberget Mine 500
24.4.4 - Comments 501
24.5 - To prevent stress waves from propagating into inhabited area 501
24.5.1 - Slot 501
24.5.2 - Vibration Barrier 503
24.6 - Concluding remarks 503
24.6.1 - Feasibility of Vibration Reduction 503
24.6.2 - Basic Principles for Vibration Reduction 503
24.6.3 - First Way to Reduce Vibration 503
24.6.4 - Second Way to Reduce Vibration 503
24.6.5 - Third Way to Reduce Vibration 503
24.6.6 - Fourth Way to Reduce Vibration 504
24.6.7 - Two Cheap and Simple Methods for Vibration Reduction 504
24.6.8 - Controlling Vibrations by Combining Different Methods 504
24.7 - Exercises 504
References 504
Chapter 25 - Special Blasting Techniques 506
25.1 - Demolition blasting 506
25.1.1 - Methods for Demolishing a Chimney 506
25.1.2 - Vibration and Safety 507
25.2 - Reinforcing soft ground by blasting 508
25.3 - Shaped charges and applications 508
25.3.1 - Shaped Charges 508
25.3.2 - Applications 510
25.4 - Well stimulation in oil and gas production 510
25.5 - Explosion welding 512
25.6 - STUMP blasting 512
25.7 - Static fragmentation agents 513
References 514
Subject Index 516
Back cover 530