5
with 50-150-120-ft pillars and the other one with 50-50-
320-ft pillars. In all scenarios, the distance between two
longwall panel edges stays the same as 520 ft (158.1 m).
Current Layout
The 3DEC model with the current design was solved with
mining the first panel. The pillar pressure and floor heave
were recorded, after panel 1 was mined.
Pillar Pressure
Figure 6 shows the pillar pressure from BPCs and modeling
results across pillars between panels 1 and 2.
The green curve in Figure 6 shows pillar pressure dur-
ing development. The blue curve shows the pillar pressure
after the panel 1 is mined. The BPCs were all initially set
at 1,800 psi (12.4 MPa) during the development stage. The
Panel 1 Panel 2 Panel 3 Panel 4
1
2
f
60 ft 90 ft 220 ft 90 ft 60 ft
Panel 1 HG#3 Panel 1 HG#1
Barrier pillar
Panel 1 HG#2
Panel 2 TG#3
Panel 2 TG#2
Panel 2 TG#1
Figure 5. Model geometry in 3DEC
Figure 6. Pillar pressure obtained from 3DEC model and the measured values by BPCs