Kiruna and Malmberget
Mining-induced ground deformations in Kiruna and ... - Impactmin
Mining-induced ground deformations in Kiruna and ... - Impactmin
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Impactmin Eurock 2012<br />
2013-04-26<br />
Mining-induced ground deformations in<br />
<strong>Kiruna</strong> <strong>and</strong> <strong>Malmberget</strong><br />
Jimmy Töyrä, LKAB
Impactmin 2012<br />
2013-04-26<br />
<strong>Kiruna</strong> year 1920…<br />
Company Hotel
Impactmin 2012<br />
2013-04-26<br />
…<strong>and</strong> 85 years later<br />
Company Hotel
Impactmin 2012<br />
2013-04-26<br />
Mining-induced ground deformations in sublevel caving<br />
Continuous<br />
deformations<br />
Discontinuous<br />
deformations<br />
Continuous<br />
deformations<br />
Deformation<br />
Zone<br />
Fracture<br />
Zone<br />
Caving<br />
Zone<br />
Deformation<br />
Zone<br />
Fracture<br />
Zone<br />
Hangingwall<br />
Caved<br />
rock<br />
Footwall<br />
Mining with sublevel caving<br />
Orebody
Impactmin 2012<br />
2013-04-26<br />
• Railroad<br />
Impact on infrastructure<br />
– New railroad has been constructed <strong>and</strong> is open for traffic.<br />
• Residential buildings<br />
– First "move-out" in 2014 ("Ullspiran" apartment complex)<br />
– Others to follow…<br />
• Other buildings<br />
– The LKAB company hotel ("Bolagshotellet") in 2015<br />
– "Hjalmar Lundbohmsgården" (the former residence of the founder<br />
of LKAB) in 2015<br />
• The bridge – mine access road (2013)<br />
• The City Hall, The Fire Brigade, etc (2017…)
Impactmin 2012<br />
2013-04-26<br />
<strong>Kiruna</strong> - view towards north<br />
City Hall<br />
<strong>Kiruna</strong> City<br />
North<br />
B Bridge<br />
LKAB Hotel<br />
"Ullspiran"<br />
Railroad<br />
Hangingwall side
Impactmin 2012<br />
2013-04-26<br />
Monitoring of ground deformations<br />
• GPS Measurements<br />
– Measurement since 2003 (total station from 1996)<br />
– 337 measurement hubs<br />
– Measurement of deformations in horizontal <strong>and</strong> vertical<br />
direction<br />
– All points measured annually; selected points measured<br />
each quarter<br />
– Reporting internally <strong>and</strong> externally each quarter:<br />
• ”Environmental criteria" – differential movement per ruling in<br />
the Swedish Environmental Court = limit for LKAB industrial<br />
area
Impactmin 2012<br />
2013-04-26<br />
Maximum allowed ground deformation<br />
Limit for allowed deformations<br />
Strain limit 0.3 % horizontally, 0.2 % vertically<br />
Example: distance 50 m<br />
max<br />
15 cm<br />
M1<br />
- more secure measurement values<br />
- shows whether mining is the cause<br />
- coupled to impact<br />
M2<br />
max<br />
10 cm
Impactmin 2012<br />
2013-04-26<br />
Monitoring results September 2012<br />
Current limit of industrial area<br />
Current limit of industrial area<br />
Environmental Criteria Criteria
Prognosis of ground deformations<br />
Impactmin 2012<br />
2013-04-26<br />
• Prognosis of location of "environmental<br />
criterion" limit for the years:<br />
- 2013<br />
- 2018<br />
- 2023<br />
Current environmental criteria<br />
2013<br />
2018<br />
2023
Impactmin 2012<br />
2013-04-26<br />
DEFORMATIONS IN THE NORTH PART OF THE MINE<br />
2010-02-08 2012-02-23<br />
2012-04-17 2012-04-25
Impactmin 2012<br />
2013-04-26<br />
Developments <strong>and</strong> Future Work<br />
• Improved deformation monitoring<br />
– Extended GPS network<br />
– InSAR-project<br />
• Improved prognosis & precision<br />
– Annually review <strong>and</strong> revision (if required) of prognosis<br />
– PhD-project at Luleå University (Ltu)
The InSAR-project<br />
Impactmin 2012<br />
2013-04-26
– High precision; few fixed hubs (except Corner<br />
Reflectors)<br />
Impactmin 2012<br />
2013-04-26<br />
– 12–15 measurements per year (24 day return period)<br />
– Further development required for winter conditions<br />
– Research project LKAB-Ltu-Cranfield University<br />
– Technology transfer MDA => LKAB
Impactmin 2012<br />
2013-04-26<br />
Thanks!<br />
Thanks!
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