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

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

weak fault condition represents a reasonable failure band fault strength used to examine the effect of very weak faults. Both elastic and plastic models are tested under these conditions. For all fault conditions, the model is subjected to a compressive stress field where σ 1 = –102.7 MPa and σ 3 = –73.4 MPa. Stress magnitudes are based on stress estimates for the 7400 Level, derived from overcoring stress measurements made by Creighton Mine. The negative sign convention in UDEC indicates compressive stress. Table 4.2: Fault parameters tested for Case 1. Fault Condition Cohesion Friction (MPa) Angle (º) Locked 50 50 Strong 5 35 Moderately Strong 0 35 Weak 0 20 Both elastic and plastic models for maximum stress, differential stress, slip, and yielding produce similar results. The locked fault condition produces low maximum and differential stresses immediately to the north and south of the excavation. Further from the excavation, high stresses form a ring around the excavation. As the cohesion is lowered at a constant friction angle, from the strong to the moderately strong model, maximum stress (Fig. 4.6) and differential stress (Fig. 4.7) is enhanced to the south and southeast of the excavation and diminished to the southwest of the excavation. When the friction angle is very low (the weak fault case), stress is diminished to the south of the excavation and high stresses are pushed farther outwards away from the excavation. Yielding in the plastic models aligns with the strike of the 118 System shear zones and further slip is induced along shear zones in proximity to the excavation. 86
The zero cohesion and low friction value (20°) condition is considered too weak to produce a realistic stress distribution. In this instance, the shear zones are weak enough to accommodate slip but the resulting magnitude of stress to the south of the excavation is diminished, whereas high stress is expected based on the occurrence of seismicity. East-west striking shear zones as well as the Footwall Shear Zone have negligible influence on stress distribution. The 1290 Shear Zones (and 400-East Shear Zone which is not represented in the model) strikes parallel to the far field stress and is thus not favourably aligned with the stress field to slip. Southwest-striking shear zones have the greatest impact on stress distribution; this system acts to redirect stress such that trends of high stress to the south of the excavation show alignment with the strike of the shear zones. This effect is enhanced with lower fault strength, though the magnitude of stress surrounding the excavation is reduced when faults are very weak. Displacement occurs along the Plum and Return Air Raise Shear Zones as right-lateral slip and is enhanced at low friction angles (Fig. 4.8). The plastic model exhibits tensile failure of the rock mass in proximity to the excavation with past and current yielding farther from the excavation (Fig. 4.9). In the strong and moderately strong cases yielding begins to localize along discontinuities. This effect is enhanced with lower fault strength. Stress trajectories for elastic and plastic models show a flow of stress around the excavation with little disturbance in the stress field near faults (see Appendix D). Stress orientations to the south of the excavation are conformable to the regional stress inversion presented in the previous chapter. 87
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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
Page 51 and 52: overprinting (Cochrane, 1991; Couls
Page 53 and 54: Table 2.4: Summary of Proterozoic t
Page 55 and 56: Both of these inferred stress direc
Page 57 and 58: are, at this time, in the process o
Page 59 and 60: Microseismic events of this subset
Page 61 and 62: 3.2.1.2 Seismic Energy (E o ) and S
Page 63 and 64: 3.2.1.4 Stress Parameters Stress pa
Page 65 and 66: located events were removed from cl
Page 67 and 68: Figure 3.7: Detected seismicity cor
Page 69 and 70: Table 3.1: Event characteristics in
Page 71 and 72: 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: Figure 4.5: (A) Model for tectonic
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 and 124: preferentially oriented fracture pl
Page 125 and 126: methodologies employed are of value
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 151 and 152: Figure B15: Events between Jan 1, 2
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Figure B19: Events between Jan 1, 2
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Cluster 1 Source Radius Asp. Radius
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Seismic Moment 10.0 9.5 9.0 8.5 8.0
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143 Peak Velocity Parameter -2.5 -2
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B.4.2 Temporal Distribution of Clus
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147 Static Stress Drop 5.0 5.5 6.0
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B.4.3 Temporal Distribution of Clus
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151 Static Stress Drop 4.0 4.5 5.0
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Frequency-Magnitude Relation for Cl
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P-axis B-axis T-axis 155 Fault Plan
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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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title of the thesis - Department of Geology - Queen's University

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