11
when designing coal pillars for underground mining stabil-
ity, particularly in deep cover conditions.
RESULTS AND DISCUSSION
The results of this study reveal a clear relationship between
the thickness and positioning of dirt bands and the strength
of coal pillars under various depths of cover, as summa-
rized in Table 10 and illustrated in Figure 11. The presence
of dirt bands within coal pillars causes a significant reduc-
tion in pillar strength, and this reduction varies depending
on the thickness of the dirt bands and the depth at which
the pillars are located. As depth increases, the impact of
dirt band thickness becomes more pronounced, reflecting
an interaction between dirt band characteristics and the
increasing overburden pressure at greater depths.
(d)
(a) (b)
(c)
(e) (f)
Figure 10. Variation in pillar strength with increasing dirt band thickness at (a) 100 m, (b) 200 m, (c) 266 m, (d) 300 m, (e)
400 m, (f) 500 m depths of cover
when designing coal pillars for underground mining stabil-
ity, particularly in deep cover conditions.
RESULTS AND DISCUSSION
The results of this study reveal a clear relationship between
the thickness and positioning of dirt bands and the strength
of coal pillars under various depths of cover, as summa-
rized in Table 10 and illustrated in Figure 11. The presence
of dirt bands within coal pillars causes a significant reduc-
tion in pillar strength, and this reduction varies depending
on the thickness of the dirt bands and the depth at which
the pillars are located. As depth increases, the impact of
dirt band thickness becomes more pronounced, reflecting
an interaction between dirt band characteristics and the
increasing overburden pressure at greater depths.
(d)
(a) (b)
(c)
(e) (f)
Figure 10. Variation in pillar strength with increasing dirt band thickness at (a) 100 m, (b) 200 m, (c) 266 m, (d) 300 m, (e)
400 m, (f) 500 m depths of cover