3
Approximately 130 ft above the study mine, the Alma
seam was previously mined using the longwall method.
Figure 5 shows the room-and-pillar layout of the study
mine (drawn in black color), highlighting the spatial posi-
tion of the selected study panel (J-3) with respect to the
overlying longwall panel (drawn in light red color). The
number of entries in the J-3 panel varies between four and
six. Barrier pillars separating the room-and-pillar panels are
positioned directly beneath the three-entry gateroad sys-
tems of the overlying 1,000-ft-wide longwall panels. This
layout ensures that the room-and-pillar panels are located
under the gob of the overlying longwall panels.
The instrumented pillar within the J-3 panel is situated
between cross-cuts 24 and 25, approximately 1,900 ft from
the last cross-cut (No. 38) and 3,100 ft from the first cross-
cut (see Figure 6). This location was selected to ensure that
the gob is fully developed at the instrumented pillar during
pillar retreating in the J-3 panel. At the instrumented pillar,
the J-3 panel is composed of six entries with a total width
of 370 ft. The barrier pillar between the J-3 and J-2 panels
is 260 ft wide, while the barrier pillar between the J-3 and
J-4 panels is 135 ft wide. The pillars at the study site are
70 ft wide and 140 ft long (center-to-center), with entry
and cross-cut widths of about 20 ft.
The overburden depth at the instrumented pillar is
approximately 1,100 ft. The critical interburden thickness
at which multiple-seam interactions would occur is 84 ft
during the development stage and 131 ft during the pillar
retreat stage, as determined by the Analysis of Coal Pillar
Stability (ACPS) program (Mark and Agioutantis, 2019).
Figure 3. Typical geological section for the study mine
Figure 4. Rib brow observed at study mine
Figure 5. Mine map showing the position of the study panel
(J-3) relative to the overlying, previously mined longwall
panel
Figure 6. Study panel (J-3) and location of study site located
between cross-cuts no. 24 and 25
Approximately 130 ft above the study mine, the Alma
seam was previously mined using the longwall method.
Figure 5 shows the room-and-pillar layout of the study
mine (drawn in black color), highlighting the spatial posi-
tion of the selected study panel (J-3) with respect to the
overlying longwall panel (drawn in light red color). The
number of entries in the J-3 panel varies between four and
six. Barrier pillars separating the room-and-pillar panels are
positioned directly beneath the three-entry gateroad sys-
tems of the overlying 1,000-ft-wide longwall panels. This
layout ensures that the room-and-pillar panels are located
under the gob of the overlying longwall panels.
The instrumented pillar within the J-3 panel is situated
between cross-cuts 24 and 25, approximately 1,900 ft from
the last cross-cut (No. 38) and 3,100 ft from the first cross-
cut (see Figure 6). This location was selected to ensure that
the gob is fully developed at the instrumented pillar during
pillar retreating in the J-3 panel. At the instrumented pillar,
the J-3 panel is composed of six entries with a total width
of 370 ft. The barrier pillar between the J-3 and J-2 panels
is 260 ft wide, while the barrier pillar between the J-3 and
J-4 panels is 135 ft wide. The pillars at the study site are
70 ft wide and 140 ft long (center-to-center), with entry
and cross-cut widths of about 20 ft.
The overburden depth at the instrumented pillar is
approximately 1,100 ft. The critical interburden thickness
at which multiple-seam interactions would occur is 84 ft
during the development stage and 131 ft during the pillar
retreat stage, as determined by the Analysis of Coal Pillar
Stability (ACPS) program (Mark and Agioutantis, 2019).
Figure 3. Typical geological section for the study mine
Figure 4. Rib brow observed at study mine
Figure 5. Mine map showing the position of the study panel
(J-3) relative to the overlying, previously mined longwall
panel
Figure 6. Study panel (J-3) and location of study site located
between cross-cuts no. 24 and 25