reflections on 30 years in ground control. analysis of retreat mining pillar stability (armps):...
TRANSCRIPT
REFLECTIONS ON 30 YEARS IN GROUND
CONTROL
Analysis of Retreat Mining Pillar Stability (ARMPS): Version 6 (2010)
62010
Side Gob B Side Gob A
Activ
e G
ob
CompositeBarrier
Ls
D
CA Ws
c4 c1
c2c3
Lb
We could spend a million dollars trying to explain why this intersection collapsed…
But then how do we explain the 100 nearby “just like it” that stayed up??!!
Other engineers have accurate knowledge of material properties and applied loads.
Because rock mass behavior is so complex, we need a different approach.
From a practical standpoint, maybe its “good enough” to know that the odds of failure were
1-in-100.
Make use of knowledge gained during “full
scale testing” of mine designs.
EMPIRICAL METHODS
Empirical methods focus on the success or failure of the full scale design.
Require a simplified model that includes all the important factors.
TAILGATE ENTRYSTABILITY
Empirical design guidelines are closely linked to reality, easy to understand, and easy to use.
Analysis of Retreat Mining Pillar Stability
(ARMPS)
Analysis of Multiple Seam
Stability (AMSS)
SYNERGY WITH NUMERICAL MODELS
Safety During Pillar Recovery:A Ground Control Success Story
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
CRANDALLCANYON
MINE DISASTER
