4
30 ft (9.1 m). Figure 3 (top) shows drilling for the BPC
installation using a double-boom bolter in the study mine.
Figure 3 (bottom) shows the insertion of a BPC cell into
the borehole.
LiDAR scanning was performed in Panel 1 HG Entry
#2 during gateroad development in November of 2023
(Figure 4) and after the first panel mineby in March of
2024. LiDAR scanning was completed using the Maptek
I-Site 8200 stationary scanner. Individual scans were taken
in succession along the entries, approximately 20 feet apart.
Each scan contained between 2.0 to 5.0 million points.
Scans collected during the November 2023 site visit were
registered together to create a single point cloud. The
process was repeated for scans taken during the March
2024 scans. The two-point clouds represent the dimensions
of Panel 1 HG Entry #2 before and after development.
Surfaces were then created and analyzed using the Maptek
PointStudio program. The dimensions of the March 2024
surface were compared to the November 2023 surface, pro-
viding changes over time in Entry 2H. The change detec-
tion results captured the roof, floor, and rib deformation
induced by the passing longwall panel.
METHODOLOGY
The objective is to find the mine layout that reduces load
transfer to the future panels and also minimize floor heave
when weak floor is encountered. The pillars in the current
design are 60-ft and 90-ft wide with a 220-ft wide barrier
center to center. We used the pillar instrumentation to vali-
date a geomechanical model of the current layout and then
used the models to study alternative layouts. Two alterna-
tive layouts were studied. One yield-yield-barrier (YYB)
with dimensions 50-150-120 ft and another one yield-sta-
ble-barrier (YSB) with dimensions 50-50-320 ft. The idea
behind the first alternative layout was to further widen the
barrier pillar and thus avoid load transfer to the next panel.
This design was studied in detail as part of a field evalua-
tion of a yield pillar system at a Kentucky longwall mine by
Mark and Barton (1988). The second alternative layout was
intended to make the stable pillar wider and thus stiffer so
the high pillar pressure in the stable pillar would break the
roof strata and thus avoid load transfer to the barrier and
the second panel.
GEOMECHANICAL MODEL
A pseudo 2D model at the location shown in Figure 1 was
constructed in 3DEC. The model lithology was taken from
drilling logs at the closest corehole to the area of interest.
Figure 5 shows the model that contains four longwall pan-
els with the current layout of the mine.
Gateroad developments and panel mining followed the
mining sequence. Each panel in the model was mined grad-
ually to reduce dynamic loading due to sudden removal of
material. Details on the gradual reduction of traction on the
mined-out boundary can be found elsewhere (Khademian
et al., 2022).
RESULTS
First, the current mine layout was modeled, and the results
of pillar pressure and floor heave were compared with the
measurements. The pillars in the current design are 60-ft
and 90-ft wide with a 220-ft-wide barrier center to center
(Figure 5). Then, two alternative layouts were studied: one
Figure 3. Drilling two 30-ft boreholes by a double-boom
bolter (top) and installing BPCs with initial pressure set to
1,800 psi (bottom)
Figure 4. Monitoring entry deformation by LiDAR scanner
before and after mineby
30 ft (9.1 m). Figure 3 (top) shows drilling for the BPC
installation using a double-boom bolter in the study mine.
Figure 3 (bottom) shows the insertion of a BPC cell into
the borehole.
LiDAR scanning was performed in Panel 1 HG Entry
#2 during gateroad development in November of 2023
(Figure 4) and after the first panel mineby in March of
2024. LiDAR scanning was completed using the Maptek
I-Site 8200 stationary scanner. Individual scans were taken
in succession along the entries, approximately 20 feet apart.
Each scan contained between 2.0 to 5.0 million points.
Scans collected during the November 2023 site visit were
registered together to create a single point cloud. The
process was repeated for scans taken during the March
2024 scans. The two-point clouds represent the dimensions
of Panel 1 HG Entry #2 before and after development.
Surfaces were then created and analyzed using the Maptek
PointStudio program. The dimensions of the March 2024
surface were compared to the November 2023 surface, pro-
viding changes over time in Entry 2H. The change detec-
tion results captured the roof, floor, and rib deformation
induced by the passing longwall panel.
METHODOLOGY
The objective is to find the mine layout that reduces load
transfer to the future panels and also minimize floor heave
when weak floor is encountered. The pillars in the current
design are 60-ft and 90-ft wide with a 220-ft wide barrier
center to center. We used the pillar instrumentation to vali-
date a geomechanical model of the current layout and then
used the models to study alternative layouts. Two alterna-
tive layouts were studied. One yield-yield-barrier (YYB)
with dimensions 50-150-120 ft and another one yield-sta-
ble-barrier (YSB) with dimensions 50-50-320 ft. The idea
behind the first alternative layout was to further widen the
barrier pillar and thus avoid load transfer to the next panel.
This design was studied in detail as part of a field evalua-
tion of a yield pillar system at a Kentucky longwall mine by
Mark and Barton (1988). The second alternative layout was
intended to make the stable pillar wider and thus stiffer so
the high pillar pressure in the stable pillar would break the
roof strata and thus avoid load transfer to the barrier and
the second panel.
GEOMECHANICAL MODEL
A pseudo 2D model at the location shown in Figure 1 was
constructed in 3DEC. The model lithology was taken from
drilling logs at the closest corehole to the area of interest.
Figure 5 shows the model that contains four longwall pan-
els with the current layout of the mine.
Gateroad developments and panel mining followed the
mining sequence. Each panel in the model was mined grad-
ually to reduce dynamic loading due to sudden removal of
material. Details on the gradual reduction of traction on the
mined-out boundary can be found elsewhere (Khademian
et al., 2022).
RESULTS
First, the current mine layout was modeled, and the results
of pillar pressure and floor heave were compared with the
measurements. The pillars in the current design are 60-ft
and 90-ft wide with a 220-ft-wide barrier center to center
(Figure 5). Then, two alternative layouts were studied: one
Figure 3. Drilling two 30-ft boreholes by a double-boom
bolter (top) and installing BPCs with initial pressure set to
1,800 psi (bottom)
Figure 4. Monitoring entry deformation by LiDAR scanner
before and after mineby