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

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

The ratio of maximum principal stresses can be expressed in terms of the angle of internal friction, 3 1 1 2 2 (tan 1) tan , (Equation 4.5) 1 2 2 (tan 1) tan when cohesion is zero (McKinnon, pers. comm., 2009; see Appendix F for derivation). This allows for zones of eligible fracture reactivation to be mapped regardless of fracture orientation. Minimum-to-maximum principal stress ratios computed for plastic and elastic models in UDEC are shown in Figure 4.22. Such figures allow fields of fault reactivation to be contoured as a function of the internal angle of friction (Fig. 4.23). This demonstrates that, based on the minimum-to-maximum principal stress ratio, there is a large area to the south of the excavation, extending to the Return Air Raise Shear Zone where cohesionless fractures in any orientation can be reactivated, even at high friction angles. This is modelled in both elastic and plastic models. Based on stress conditions, slip is possible even in the yield zone, though seismogenic slip is not expected. Figure 4.22: Ratio of minimum-to-maximum principal stress for (A) elastic model; (B) plastic model. 98
Figure 4.23: Contoured domains of slip on cohesionless fractures at different angles of internal friction for (A) elastic model; (B) plastic model. 4.6.2 Crack Initiation The initiation of new brittle failure is possible at stress levels much lower than the peak strength of the rock mass (Schultz, 1996). Crack initiation can be expected at levels from 0.3-0.5 σ UCS (Cai et al., 2004) and yield is modelled to occur between 0.4-0.5σ UCS for the Creighton granite (Diederichs, 2003). Fracture coalescence can occur from 0.7-0.8 σ UCS (Falmagne, 2001). Such thresholds have been applied to the 7400 Level using modelled stresses and the uniaxial compressive strength of footwall rocks to explore crack initiation as a mechanism for microseismicity in the Creighton Deep. The limits for fracture initiation and coalescence are shown in Figure 4.24. Crack initiation can also be described by differential stress, when its magnitude is a fraction of the peak strength. Differential stress threshold for the Lac du Bonnet granite is measured in the range of (σ 1 – σ 3 ) = 0.3 to 0.4σ UCS to (Falmagne, 2001). This threshold is used as an analogue to the Creighton granite. Differential stress plots outline zones of potential crack initiation (Fig. 4.24). 99
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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
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 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: clustering are indications of rock
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 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
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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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