6
red dots show the BPC gauge values after panel 1 is mined.
A comparison among the modeling results and BPC read-
ings shows relatively good agreement.
The BPC readings in the stable and barrier pillars on the
first panel headgate side show particularly less pressure than
the modeling results. This is because we stopped recording
data and removed dataloggers when the first panel reached
the monitoring site. So, the full abutment loading was not
captured by those BPCs.
The most important comparison is for the pressure in
the stable and yield pillars in the tailgate of panel 2. Both
modeling results and BPC readings show that there is load
transfer from panel 1 mining to the panel 2 tailgate. The
BPCs within the stable pillar in the tailgate of panel 2 in
Figure 6 show an increase of 2,050 psi (14.1 MPa) and
2,440 psi (16.8 MPa). Figure 7 shows the BPC readings
within the stable pillar in the panel 2 tailgate over time with
panel 1 face locations.
The pressure in the big pillar (measured by BPC 4
and 5) started rising 250 ft (76 m) outby and kept increas-
ing even 3,150 ft inby the face (the last measurement on
05/28/2024) to about 4,000 psi (28 MPa). As mentioned
before, this means there was a 2,050 psi (14.1 MPa) to
2,440 psi (16.8 MPa) increase in pillar pressure from the
development stage. From Figure 6, this pillar pressure
increase was 1,160 psi (8 MPa) in the models. The BPCs in
the yield pillar in the tailgate of panel 2 show an increase
of 1,634 psi (11.3 MPa). The modeling results in this loca-
tion show an increase of 971 psi (6.7 MPa) in this location.
These results plus the author’s observation of rib sloughing
and mild floor heave (less than 1 ft (0.3 m)) in the tailgate
of panel 2 confirmed that there is significant load transfer
from panel 1 to panel 2.
Floor Heave
After mining panel 1, the heave in the floor was plotted.
Figure 8 and Figure 9 show the modeling results for the
profile of floor heave after mining panel 1. From the mod-
els, Panel 1 HG Entry #2 showed the highest heave of 3.4 ft
(1.1 m). From the models, the load transfer to the panel 2
tailgate also caused floor heave of 0.8 ft (0.24 m) and 0.3 ft
(0.1 m) in Panel 2 TG Entry #3 and #2, respectively.
Figure 10 shows initial results of LiDAR scanning.
The point cloud shown in Figure 10 was collected during
the March 2024 scanning event and is colored based on
the height from an arbitrary floor line (red). The original
Figure 7. BPC readings in the stable pillar in the Panel 2
tailgate
Figure 8. Floor heave profile from modeling results after
panel 1 was completed
Figure 9. Floor heave profile from modeling results after
panel 1 was completed
red dots show the BPC gauge values after panel 1 is mined.
A comparison among the modeling results and BPC read-
ings shows relatively good agreement.
The BPC readings in the stable and barrier pillars on the
first panel headgate side show particularly less pressure than
the modeling results. This is because we stopped recording
data and removed dataloggers when the first panel reached
the monitoring site. So, the full abutment loading was not
captured by those BPCs.
The most important comparison is for the pressure in
the stable and yield pillars in the tailgate of panel 2. Both
modeling results and BPC readings show that there is load
transfer from panel 1 mining to the panel 2 tailgate. The
BPCs within the stable pillar in the tailgate of panel 2 in
Figure 6 show an increase of 2,050 psi (14.1 MPa) and
2,440 psi (16.8 MPa). Figure 7 shows the BPC readings
within the stable pillar in the panel 2 tailgate over time with
panel 1 face locations.
The pressure in the big pillar (measured by BPC 4
and 5) started rising 250 ft (76 m) outby and kept increas-
ing even 3,150 ft inby the face (the last measurement on
05/28/2024) to about 4,000 psi (28 MPa). As mentioned
before, this means there was a 2,050 psi (14.1 MPa) to
2,440 psi (16.8 MPa) increase in pillar pressure from the
development stage. From Figure 6, this pillar pressure
increase was 1,160 psi (8 MPa) in the models. The BPCs in
the yield pillar in the tailgate of panel 2 show an increase
of 1,634 psi (11.3 MPa). The modeling results in this loca-
tion show an increase of 971 psi (6.7 MPa) in this location.
These results plus the author’s observation of rib sloughing
and mild floor heave (less than 1 ft (0.3 m)) in the tailgate
of panel 2 confirmed that there is significant load transfer
from panel 1 to panel 2.
Floor Heave
After mining panel 1, the heave in the floor was plotted.
Figure 8 and Figure 9 show the modeling results for the
profile of floor heave after mining panel 1. From the mod-
els, Panel 1 HG Entry #2 showed the highest heave of 3.4 ft
(1.1 m). From the models, the load transfer to the panel 2
tailgate also caused floor heave of 0.8 ft (0.24 m) and 0.3 ft
(0.1 m) in Panel 2 TG Entry #3 and #2, respectively.
Figure 10 shows initial results of LiDAR scanning.
The point cloud shown in Figure 10 was collected during
the March 2024 scanning event and is colored based on
the height from an arbitrary floor line (red). The original
Figure 7. BPC readings in the stable pillar in the Panel 2
tailgate
Figure 8. Floor heave profile from modeling results after
panel 1 was completed
Figure 9. Floor heave profile from modeling results after
panel 1 was completed