reflections on 30 years in ground control. analysis of retreat mining pillar stability (armps):...
Post on 03-Jan-2016
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From a practical standpoint, maybe its “good enough” to know that the odds of failure were
1-in-100.
0
1
2
3
4
1995 1997 1999 2001 2003 2005
Nu
mb
er o
f F
atal
Ro
of
Fal
ls Double Fatality
Fatal Roof Falls During Retreat Mining1995-2005
0
1
2
3
4
1995 1997 1999 2001 2003 2005 2007 2009 2011
Num
ber o
f Fat
al R
oof F
alls
Double Fatality
Fatal Roof Falls During Retreat Mining1995-2011
One fatal roof fall in six years
Leave the final stump
Use extra roof bolt support
Mobile Roof
Supports
Technologies that made the difference
Retreat Mining
~ 30 million tons/year~ 400 tons/pillar~ 80,000 pillars/year
~ 200 retreat mines
~ 400 pillars/mine/year
Retreat Mining
~ 80,000 pillars/year~ 400 pillars/mine/year
Prior to 2005, nationwide there were ~ 2 fatals/year
~ Rate was 1 fatal/40,000 pillars
Typical mine: One fatal every 100 years
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