Large Seismic Event Mitigation
Zachary Mayer
May 24 2012
Agenda
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What Happened
Project Goals and Results
Timeline of Geotechnical Studies
Risk Mitigation
Ground Support Standards
Geotechnical Modelling Results
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2009 & 2011
Seismic Events
• Jan 6/2009: 3.8 Mn event on 7000L.
• June 15/2009: 3.1 Mn event on 7500L.
• Aug 21/2011: 3.2 Mn event on 7500L.
• Sept 13/2011: 3.8 Mn event on 7000L.
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Seismic Project
Goal and Results
Determine what happened
• Horizontal stress fault slip in pillar. Structure & geometry.
Can seismic models reproduce the events?
• Yes – now have a better understanding.
Can we control the events?
• New mining sequence will not eliminate seismic events,
but should reduce maximum magnitude going forward.
Can we manage the impact of large events?
• Yes - New support standards are effective in reducing
damage/risk. Additional reinforcement in key areas.
• Re-entry protocols. Expanded the post-blast closure areas
and increased personnel re-entry times.
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Timeline of
Geotechnical Risk Studies
and Mitigation Efforts
2004
Mine-D
Seismic System Upgrade
2001
2000
1996
Deep Mining
Forum
2006
Begin
Geotechnical Risk
Assessments
2003
Begin Mine D
modelling
2000
Mine D Feasibility
2002
2003
2004
2005
2006
2007
2012
Forensic +
Forward
Communication Modelling
Screens
2009
Industry/Technical
Review of Events
& Investigation
2007
Implement MS-RAP
software
2002
Begin Analysis of 3-Mine
Phase 2 sequence
2008
2010
External
Audits
2009
Add GC Staff
2009
2010
2011
2012
Industry/
Expert
Tehnical
Peer Review
Panel Review
2011
2012
2009
2011
Implement Re-Entry
2008
Seismic System
Protocols
Annual Update
Upgrade
of Geotechnical
2010 (Palladin D-Mine)
Mine Design Doc
Update
2012
Risk Register
Alternate Mine
2007
Sequence
ESS Modelling
2009
Selected
Begin Enhanced
Support
2012
Installation Program
Seismic
2006
Overhaul Support
Strategy
2004
First Cone-Bolts
Installed
large seismic events
2009
Sequence Changes
Support Standard Upgrades
Modelling
Monitoring
2010
Tomography
2010
Seismic System Upgrade
(Palladin)
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Ground Control Experts
Involved in Kidd Study
(2009-2012)
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Patrick Andrieux – Itasca Consulting, Sudbury
David Beck – Beck Engineering, Australia
Wilson Blake – Independent Consultant, USA
Richard Brummer – Itasca Consulting, Sudbury
John Fedorowich – Itasca Consulting, Sudbury
Anneta Forsythe – ex-Kidd/Itasca now Vale, Sudbury
John Henning – ex-Kidd now Goldcorp, Timmins
Marty Hudyma – Laurentian University, Sudbury
Steve McKinnon – Queens University, Kingston
Rob Mercer – Knight Piesold, North Bay
Brad Simser – Xstrata Nickel, Sudbury
Graham Swan – Ex-Falconbridge, Sudbury
Erik Westmin – Virginia Tech, USA
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Geotechnical Risk Studies
Additional Mitigation Efforts
2011-2012
• Geotechnical analysis through detailed stress and
structural models by 2 different consultants.
• Historical sequence modelling back to 2001 to try to recreate and understand events.
Stress Model
Displacement model
Seismic Velocity
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Risk Mitigation
• Enhanced support installation from 6000L to 9500L – the PPE of
the mine.
• Re-entry protocols. Expanded the post-blast closure areas and
increased personnel re-entry times.
• Currently shutting down between 2-4 levels for 12+ hours
approximately 140 times/year.
• Revised mining sequence.
• Revised support standards (lower screen & bolt to floor).
• Six Sigma project– single-pass “in cycle” enhanced support.
• Ongoing monitoring for deviation - SMART cable installation in
intersections.
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Geotechnical Risk Studies
Additional Mitigation Efforts
2011-2012
• Forensic data mining looking for correlations.
• Confirming and adjusting ground support in
damaged areas.
• Additional cable bolting in sensitive areas.
• Instrumenting more intersections.
• Investigating new seismic monitoring technology.
• Passive seismic tomography study.
• Additional microseismic system upgrades.
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Damage Comparison
2009 vs. 2011
Enhanced Support Works
3.8Mn - Jan 2009 71-01S
Complete collapse of back
After 2009 rockburst:
• 4 intersections collapsed
• Drift damaged over hundreds of meters
• Several areas inaccessible
3.8Mn - Sept 2011 71-01S
Failure limited to bottom half of walls
After 2011 rockburst:
• No intersections collapsed
• Walls damaged over tens of meters
• No areas inaccessible
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Enhanced Support Works
71-82 XC
enhanced support installed
71-82 XC
after 3.8Mn event
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7700L Refuge Station
Upgrades
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7400L Ramp Upgrades
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69-S40 ACC
Single-Pass Enhanced
Support Installed “In Cycle”
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Modelling Results Example
Seismic Potential 2013
Original Mining Plan
New Mining Plan
Red areas
represent
potential
seismic
zones
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Conclusion
• New technology and tools provided better
analysis and planning information.
• Have modelled that we can do something
different - new mining sequence reduces risk.
• Expert consensus obtained on path forward.
• Enhanced support is doing it’s job.
• Expanded re-entry protocols keeping people out
of harms way.
Questions?
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