1
25-031
Enhancing Pillar Stability in a Deep-Cover Longwall Mine Using
the LaModel Program: A Comparative Analysis
Morgan M. Sears
CDC NIOSH, Pittsburgh, PA
ABSTRACT
The stability of gateroad pillars is crucial in deep-cover long-
wall mining, especially during transitions to wider panel
layouts. This study evaluates the transition from a 700-foot
to a 1,000-foot panel layout with an inter-panel barrier in
a deep-cover longwall mine in Southwestern Virginia to
identify a configuration that enhances stability and reduces
operational risks. Using the LaModel program, three pillar
configurations were simulated to assess their performance
based on stress distributions and pillar safety factors. These
included the previously used 4-Entry Yield-Abutment-Yield
layout, the current 3-Entry Yield-Abutment layout with a
220-ft inter-panel barrier, and the proposed 3-Entry Yield-
Yield layout with a 320-ft inter-panel barrier. The findings
of this study suggest that the proposed 3-Entry Yield-Yield
pillar layout is more effective in managing stresses in deep-
cover mining environments. By optimizing pillar place-
ment and improving load management, this layout could
positively impact mineworker safety and health. The study
underscores the importance of advanced simulation tools in
developing innovative solutions to address the challenges of
modern longwall mining operations.
INTRODUCTION
The stability of underground mine workings is crucial in
deep-cover longwall coal mining, particularly in regions
such as Southwestern Virginia, where mining depths
often exceed 2,000 ft. Ensuring gateroad pillar stability is
vital to maintaining safe mining operations in these envi-
ronments. During the transition from a 700-foot panel lay-
out to a 1,000-foot layout with an inter-panel barrier in
the Pocahontas #3 seam, new ground control challenges in
managing stress emerged, primarily in excessive floor heave.
Advancements in computational modeling, mainly
using LaModel (Heasley, 1998), enable more detailed
simulations of stress distributions and deformations under
such demanding conditions. This study leverages LaModel
to compare the performance of three gateroad pillar layouts
used or proposed in this mine. The objective is to identify
design improvements that enhance stability and mitigate
adverse ground control conditions, such as floor heave, par-
ticularly under wider panel configurations.
This research focuses on the analysis of stress redistri-
butions and pillar safety factors across the three pillar lay-
outs: the previous 4-Entry Yield-Abutment-Yield (Y-A-Y)
layout, the current 3-Entry Yield-Abutment (Y-A) layout
with an inter-panel barrier, and a proposed 3-Entry Yield-
Yield (Y-Y) layout (Mark and Barton, 1988 Barron et al.,
1994) with an inter-panel barrier. The insights derived
from these analyses are expected to offer valuable insight for
optimizing gateroad design and improving ground stability
in longwall mining operations under deep cover.
MINE LAYOUT
Taking a closer look at the three pillar layouts, the first
layout, successfully used for several years, is a 4-Entry sys-
tem with a Y-A-Y pillar arrangement and a panel width of
705 ft. The pillars in this configuration comprise 175-ft
by 450-ft abutment pillars and 50-ft by 150-ft yield pil-
lars (C-C), effectively managing stress concentrations in the
gateroad (see Figure 1).
The current layout incorporates a 3-Entry system with
a 220-ft (C-C) inter-panel barrier and was introduced
to accommodate a 1,000-foot-wide panel. This design
employs a Y-A pillar system with 90-ft by 160-ft abutment
pillars and 60-ft by 160-ft yield pillars (C-C) (see Figure 2).
However, challenges have arisen with this layout, par-
ticularly concerning floor heave observed in the tailgate
entries on the far side of the barrier. These issues prompted
a reevaluation of the design to find alternative solutions
25-031
Enhancing Pillar Stability in a Deep-Cover Longwall Mine Using
the LaModel Program: A Comparative Analysis
Morgan M. Sears
CDC NIOSH, Pittsburgh, PA
ABSTRACT
The stability of gateroad pillars is crucial in deep-cover long-
wall mining, especially during transitions to wider panel
layouts. This study evaluates the transition from a 700-foot
to a 1,000-foot panel layout with an inter-panel barrier in
a deep-cover longwall mine in Southwestern Virginia to
identify a configuration that enhances stability and reduces
operational risks. Using the LaModel program, three pillar
configurations were simulated to assess their performance
based on stress distributions and pillar safety factors. These
included the previously used 4-Entry Yield-Abutment-Yield
layout, the current 3-Entry Yield-Abutment layout with a
220-ft inter-panel barrier, and the proposed 3-Entry Yield-
Yield layout with a 320-ft inter-panel barrier. The findings
of this study suggest that the proposed 3-Entry Yield-Yield
pillar layout is more effective in managing stresses in deep-
cover mining environments. By optimizing pillar place-
ment and improving load management, this layout could
positively impact mineworker safety and health. The study
underscores the importance of advanced simulation tools in
developing innovative solutions to address the challenges of
modern longwall mining operations.
INTRODUCTION
The stability of underground mine workings is crucial in
deep-cover longwall coal mining, particularly in regions
such as Southwestern Virginia, where mining depths
often exceed 2,000 ft. Ensuring gateroad pillar stability is
vital to maintaining safe mining operations in these envi-
ronments. During the transition from a 700-foot panel lay-
out to a 1,000-foot layout with an inter-panel barrier in
the Pocahontas #3 seam, new ground control challenges in
managing stress emerged, primarily in excessive floor heave.
Advancements in computational modeling, mainly
using LaModel (Heasley, 1998), enable more detailed
simulations of stress distributions and deformations under
such demanding conditions. This study leverages LaModel
to compare the performance of three gateroad pillar layouts
used or proposed in this mine. The objective is to identify
design improvements that enhance stability and mitigate
adverse ground control conditions, such as floor heave, par-
ticularly under wider panel configurations.
This research focuses on the analysis of stress redistri-
butions and pillar safety factors across the three pillar lay-
outs: the previous 4-Entry Yield-Abutment-Yield (Y-A-Y)
layout, the current 3-Entry Yield-Abutment (Y-A) layout
with an inter-panel barrier, and a proposed 3-Entry Yield-
Yield (Y-Y) layout (Mark and Barton, 1988 Barron et al.,
1994) with an inter-panel barrier. The insights derived
from these analyses are expected to offer valuable insight for
optimizing gateroad design and improving ground stability
in longwall mining operations under deep cover.
MINE LAYOUT
Taking a closer look at the three pillar layouts, the first
layout, successfully used for several years, is a 4-Entry sys-
tem with a Y-A-Y pillar arrangement and a panel width of
705 ft. The pillars in this configuration comprise 175-ft
by 450-ft abutment pillars and 50-ft by 150-ft yield pil-
lars (C-C), effectively managing stress concentrations in the
gateroad (see Figure 1).
The current layout incorporates a 3-Entry system with
a 220-ft (C-C) inter-panel barrier and was introduced
to accommodate a 1,000-foot-wide panel. This design
employs a Y-A pillar system with 90-ft by 160-ft abutment
pillars and 60-ft by 160-ft yield pillars (C-C) (see Figure 2).
However, challenges have arisen with this layout, par-
ticularly concerning floor heave observed in the tailgate
entries on the far side of the barrier. These issues prompted
a reevaluation of the design to find alternative solutions