8
The heave in Entry 3T was reduced by the YBS design
by 32%. The YYB design showed a further decrease in
heave by 54%. Both the YYB and YSB designs reduced the
heave in Entry 2T by 56%.
DISCUSSION
Extensive instrumentation of pillars and entries in a long-
wall mine was used to evaluate a new mine design. The
BPC instrumentations show that there was a significant
load transfer from the first panel to the second while the
220-ft-wide barrier pillar was supposed to isolate each panel.
LiDAR scanning also showed significant floor heaves in the
middle entry in the headgate of panel 1. A geomechani-
cal model was developed and confirmed the instrumenta-
tion monitoring results of pillar pressure and floor heave.
Then, two mine layout alternatives were evaluated in terms
of load transfer and floor heave. The results showed that
Yield-Stable-Barrier design with dimensions 50-150-120 ft
led to minimum load transfer and floor heave in critical
areas. The second design of Yield-Barrier with dimensions
(50-50-320 ft) were shown to be close to the YSB design
but with the advantage of less development time because it
led to shorter crosscuts.
CONCLUSION
A study was conducted in a deep longwall mine in Virginia
in a mining area with new single-panel-district design
where each panel was isolated by a 220-ft-wide barrier pil-
lar. The pillars in the headgate of the first panel and tailgate
of the second panel were instrumented along with the bar-
rier pillar separating the panels. The instrumentation results
showed that there was a transfer of load from the first panel
to the tailgate of the second panel during mining of the first
panel. The results were also confirmed by geomechanical
models that were then used to evaluate an alternative mine
layout with respect to load transfer and floor heave.
Modeling results show that widening the barrier pillar
by changing the layout to a two-yield pillar can reduce load
transfer and floor heave in the entries of the next panel tail-
gate side. However, widening the stable pillar and narrow-
ing the barrier pillar can further stabilize the entry while
further reducing the load transfer to the second panel.
Other operational and technical aspects need to be evalu-
ated for comprehensive analyses of each layout. However,
the results show how geomechanical models can be used
for evaluating and thus optimizing mine designs, reducing
ground control challenges and improving mine safety.
LIMITATIONS
This study is built on several, albeit reasonable, assump-
tions about the accuracy of instrumentation tools and rock
mechanical properties used in the geomechanical models.
Designs were evaluated based on only two criteria: pillar
pressure and floor heave. However, many other aspects need
to be evaluated such as mine ventilation, mine economy,
development rate, seismic hazards, 3D model of the mining
area and so on. In addition, conclusions in this paper may
not be applicable to other mines with similar conditions.
Mine layout effects on ground control challenges depend
on the geology, overburden depth, surface topography, and
mining conditions that need to be studied on a case-by-case
basis.
DISCLAIMER
The findings and conclusions in this paper are those of the
authors and do not necessarily represent the official posi-
tion of the National Institute for Occupational Safety
and Health (NIOSH), Centers for Disease Control and
Prevention (CDC). Mention of any company or product
does not constitute endorsement by NIOSH.
REFERENCES
Englund, K. J., and Briggs, G. (1974). Sandstone
Distribution Patterns in the Pocahontas Formation
of Southwest Virginia and Southern West Virginia.
In Carboniferous of the Southeastern United States
(Vol. 148, pp. 0): Geological Society of America.
Khademian, Z., Beale, J., Hicks, S, Fuller, J., Agioutantis, Z.,
Justice, Q. (2024). “Seismic potential forecasting in a
deep longwall mine.” In the Proceedings of the 43rd
International Conference on Ground Control in
Mining, July 21–24, 2024 |Canonsburg, PA.
Figure 13. Average floor heave in different mine layouts
The heave in Entry 3T was reduced by the YBS design
by 32%. The YYB design showed a further decrease in
heave by 54%. Both the YYB and YSB designs reduced the
heave in Entry 2T by 56%.
DISCUSSION
Extensive instrumentation of pillars and entries in a long-
wall mine was used to evaluate a new mine design. The
BPC instrumentations show that there was a significant
load transfer from the first panel to the second while the
220-ft-wide barrier pillar was supposed to isolate each panel.
LiDAR scanning also showed significant floor heaves in the
middle entry in the headgate of panel 1. A geomechani-
cal model was developed and confirmed the instrumenta-
tion monitoring results of pillar pressure and floor heave.
Then, two mine layout alternatives were evaluated in terms
of load transfer and floor heave. The results showed that
Yield-Stable-Barrier design with dimensions 50-150-120 ft
led to minimum load transfer and floor heave in critical
areas. The second design of Yield-Barrier with dimensions
(50-50-320 ft) were shown to be close to the YSB design
but with the advantage of less development time because it
led to shorter crosscuts.
CONCLUSION
A study was conducted in a deep longwall mine in Virginia
in a mining area with new single-panel-district design
where each panel was isolated by a 220-ft-wide barrier pil-
lar. The pillars in the headgate of the first panel and tailgate
of the second panel were instrumented along with the bar-
rier pillar separating the panels. The instrumentation results
showed that there was a transfer of load from the first panel
to the tailgate of the second panel during mining of the first
panel. The results were also confirmed by geomechanical
models that were then used to evaluate an alternative mine
layout with respect to load transfer and floor heave.
Modeling results show that widening the barrier pillar
by changing the layout to a two-yield pillar can reduce load
transfer and floor heave in the entries of the next panel tail-
gate side. However, widening the stable pillar and narrow-
ing the barrier pillar can further stabilize the entry while
further reducing the load transfer to the second panel.
Other operational and technical aspects need to be evalu-
ated for comprehensive analyses of each layout. However,
the results show how geomechanical models can be used
for evaluating and thus optimizing mine designs, reducing
ground control challenges and improving mine safety.
LIMITATIONS
This study is built on several, albeit reasonable, assump-
tions about the accuracy of instrumentation tools and rock
mechanical properties used in the geomechanical models.
Designs were evaluated based on only two criteria: pillar
pressure and floor heave. However, many other aspects need
to be evaluated such as mine ventilation, mine economy,
development rate, seismic hazards, 3D model of the mining
area and so on. In addition, conclusions in this paper may
not be applicable to other mines with similar conditions.
Mine layout effects on ground control challenges depend
on the geology, overburden depth, surface topography, and
mining conditions that need to be studied on a case-by-case
basis.
DISCLAIMER
The findings and conclusions in this paper are those of the
authors and do not necessarily represent the official posi-
tion of the National Institute for Occupational Safety
and Health (NIOSH), Centers for Disease Control and
Prevention (CDC). Mention of any company or product
does not constitute endorsement by NIOSH.
REFERENCES
Englund, K. J., and Briggs, G. (1974). Sandstone
Distribution Patterns in the Pocahontas Formation
of Southwest Virginia and Southern West Virginia.
In Carboniferous of the Southeastern United States
(Vol. 148, pp. 0): Geological Society of America.
Khademian, Z., Beale, J., Hicks, S, Fuller, J., Agioutantis, Z.,
Justice, Q. (2024). “Seismic potential forecasting in a
deep longwall mine.” In the Proceedings of the 43rd
International Conference on Ground Control in
Mining, July 21–24, 2024 |Canonsburg, PA.
Figure 13. Average floor heave in different mine layouts