title of the thesis - Department of Geology - Queen's University

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$Fayek & Kyser 2000 uraninite fractionations.pdf - Queen's University$

Deep. Little evidence, however, has been found in this thesis to support displacements along mine-scale discontinuities as a source of seismicity in the footwall region to the south of the excavation. Results indicate that seismicity in the Creighton Deep is the product of a degradation process. As stress flows around the excavation, zones of high stress are created that coincide with zones of preferential seismic activity. Shear zones slightly modify the stress field to the south of the excavation by realigning high stresses with the strike of major structures and reducing stress to the southwest of the excavation where little seismicity is observed. Shear zones in Creighton Deep thus only play a secondary role in the production of seismicity by modifying the stress state. Seismicity on mine levels in the Creighton Deep can be explained by the diffusion of rock mass degradation. Immediately to the north and south of the excavation, rock is heavily fractured and permanently strained in a yield zone. The rock mass in this zone cannot accommodate high stress and this stress is transferred to the peripheral damage zone. Little to no seismicity is recorded within the yield zone and this area is modelled as having yielded and as having low stress and low differential stress. The damage zone has been demonstrated to be an area of damage accumulation, where crack initiation and fracture reactivation are possible seismic sources. This zone contains the highest modelled stresses and hosts the densest seismic activity. It is recognized as a zone of increased seismic hazard. Rock is intact beyond the damage zone and little seismicity occurs remote to mine drifts. Stress levels in the damage zone are near background levels. Large events are often associated with structure, and in many instances fault slip is the source of high magnitude seismic events. While seismic and stress analyses conducted in this thesis have not revealed any significant relationship between mining-induced seismicity and structure, the 108
methodologies employed are of value to other underground environments excavating in disturbed ground, and may show more positive results in cases where faults are geologically weak. 5.3 Recommendations for Future Work Based on the results of this study, the following recommendations are made: Continued monitoring of seismic event parameters should be carried out in order to identify signs of further rock mass degradation. Extra caution should be given to the area identified as Cluster 1. This is identified as an area of increased hazard and continues to be a source of energetic events. Further studies of events in this area may help characterize and understand anomalous activity in this area. Additional triaxial sensors are recommended to improve location accuracy and to facilitate further seismic studies in the Creighton Deep. Denser spacing in key areas of interest may also facilitate studies. A comparison of fault plane solutions for microseismic events with joint fabric on the 7400 Level is suggested as future work. A correlation with joint planes may explain the deviation of estimated fault plane orientations from mapped fault orientations. Moment tensor inversion for microseismic events is recommended to study the damage process and characterize seismicity. Mechanisms such as crack dilation and closure could be identified using this method. Moment tensor inversion may also be a suitable method for studying events in Cluster 1. Further analysis of macroseismic events is recommended once the triaxial strong ground motion system is calibrated. Waveforms recorded by the calibrated triaxial system will allow 109
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THE INFLUENCES OF STRESS AND STRUCT
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esulting in increased stress to the
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Table of Contents Abstract.........
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4.6.1 Fracture Reactivation........
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List of Figures Figure 1.1: Locatio
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Figure 3.23: Preliminary stress inv
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Figure B11: Events between Jan 1, 2
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List of Tables Table 2.1: Geologica
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Chapter 1 Introduction 1.1 Backgrou
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Figure 1.1: Location of Sudbury and
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Chapter 2 Geological Assessment of
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ack breccia and sediments later dep
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Murray Fault, the principal fault o
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2.2 Local Geology of Creighton Mine
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B West East B’ Figure 2.4B: Longi
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Table 2.2: Fault systems within the
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Table 2.3: Summary of Fault Charact
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Figure 2.6: (A) Damage to shotcrete
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Figure 2.7: (A) The 1290 Shear Zone
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Figure 2.8: Images of (A) the 400-E
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Figure 2.9: (A) Photograph of the c
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Figure 2.10 (A) Shear foliation, in
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Figure 2.11: Thin sections of the F
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(Fig. 2.12B). Reduction of quartz g
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2.3.11 Late-Stage Fractures The you
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overprinting (Cochrane, 1991; Couls
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Table 2.4: Summary of Proterozoic t
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Both of these inferred stress direc
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are, at this time, in the process o
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Microseismic events of this subset
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3.2.1.2 Seismic Energy (E o ) and S
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3.2.1.4 Stress Parameters Stress pa
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located events were removed from cl
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Figure 3.7: Detected seismicity cor
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Table 3.1: Event characteristics in
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Table 3.3: Summary of relevant para
Page 73 and 74: ) Damage Zone The rock mass in the
Page 75 and 76: quadrants of dilatation and compres
Page 77 and 78: Figure 3.12: Lower hemisphere equal
Page 79 and 80: mechanism shows that over 57% of th
Page 81 and 82: Figure 3.16: Classification of prin
Page 83 and 84: Figure 3.18: Contoured P-axis, B-ax
Page 85 and 86: Figure 3.20: Distribution of double
Page 87 and 88: This parameter reflects the magnitu
Page 89 and 90: Figure 3.23: Preliminary stress inv
Page 91 and 92: Figure 3.25: Equal area stereonet s
Page 93 and 94: Figure 3.27: (A) Maximum principal
Page 95 and 96: 4.2 Numerical Methods Phase 2 and U
Page 97 and 98: Stress-strain relationships are use
Page 99 and 100: Rock mass failure is governed by th
Page 101 and 102: Figure 4.5: (A) Model for tectonic
Page 103 and 104: The zero cohesion and low friction
Page 105 and 106: Figure 4.9: Model of yielding for C
Page 107 and 108: Figure 4.11: Model of differential
Page 109 and 110: Figure 4.14: Model of maximum stres
Page 111 and 112: stress field model. There is little
Page 113 and 114: clustering are indications of rock
Page 115 and 116: Figure 4.23: Contoured domains of s
Page 117 and 118: Figure 4.24: Fracture initiation th
Page 119 and 120: seismic Cluster 1, which correspond
Page 121 and 122: contains energetic events and is no
Page 123: preferentially oriented fracture pl
Page 127 and 128: References Alcott, J. M., Kaiser, P
Page 129 and 130: Galkin, V., Mungall, J. (2005). Str
Page 131 and 132: Mungall, J. E., & Hanley, J. J. (20
Page 133 and 134: Appendix A Geological Maps and Samp
Page 135 and 136: A.2 Level Plans with Sample Locatio
Page 137 and 138: Figure A3: 7400 Level, modified for
Page 139 and 140: Figure A5: 7680 Level, modified for
Page 141 and 142: Figure A7: 7940 Ramp, modified from
Page 143 and 144: MICROSEISMIC EVENTS Source Radius A
Page 145 and 146: 2006 Event Frequency with Depth 600
Page 147 and 148: B.2 Spatial Distribution of Seismic
Page 149 and 150: Figure B11: Events between Jan 1, 2
Page 155 and 156: Cluster 1 Source Radius Asp. Radius
Page 157 and 158: Seismic Moment 10.0 9.5 9.0 8.5 8.0
Page 159 and 160: 143 Peak Velocity Parameter -2.5 -2
Page 161 and 162: B.4.2 Temporal Distribution of Clus
Page 163 and 164: 147 Static Stress Drop 5.0 5.5 6.0
Page 165 and 166: B.4.3 Temporal Distribution of Clus
Page 167 and 168: 151 Static Stress Drop 4.0 4.5 5.0
Page 169 and 170: Frequency-Magnitude Relation for Cl
Page 171 and 172: P-axis B-axis T-axis 155 Fault Plan
Page 173 and 174: P-axis B-axis T-axis Fault Plane 1
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P-axis B-axis T-axis Fault Plane 1
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P-axis B-axis T-axis Fault Plane 1
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D.1.1: Case 1 Models Figure D1: Cas
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Figure D3: Case 1, elastic models s
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A B C D Figure D5: Case 1, plastic
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A B C D Figure D7: Case 1, plastic
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D.1.2: Case 2 Models A B C D Figure
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D.1.3: Case 3 Models A B C Figure D
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D1.4 Tectonic Loading Models Figure
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D.2 Discussion of Phase 2 Models El
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Staged models were created in which
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Figure D17 (A) Elastic model showin
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Figure D19 (A) Elastic model showin
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• Similar damage zones surroundin
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; ;================================
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change jmat=1 range 0,1564.64 0,156
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crack (845.579,718.676) (787.063,57
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;===plum=== crack (0,355.2371429) (
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crack (866.14,726.44) (838.2,737.61
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crack (838.2,737.616) (815.848,771.
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crack (815.848,771.144) (815.848,78
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;===== define sub block ===========
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E.9 S3:S1 Model for fracture reacti
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yval= abs(z_syy(zi)) xyval= abs(z_s
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and rearranged to , (Equation F4) .
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Such that , (Equation F19) I is the
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