3
C‑1 (Figure 2). Panel No. C‑2 was initially developed using
semi-mechanized conventional Bord and Pillar Mining
Method (BPMM). The development occurred in two dis-
tinct sections: one along the middle horizon and another
along the top section, with the immediate roof consisting
of sandstone.
The field investigation revealed that a significant por-
tion of the panel was initially developed using semi-mech-
anized BPMM, with gallery dimensions of 3.6 m in width
and 2.5 m in height. However, to facilitate CM opera-
tions, the gallery size was later widened to 6 m in width (as
shown in Figure 3) and heightened to 5 m. This expansion,
which exceeded statutory provisions, was permitted by the
Directorate General of Mines Safety (DGMS), India, to
allow sufficient maneuvering space for the CM equipment.
The increased gallery size posed challenges for roof stability,
as the immediate roof of coal and shale was found to be
fractured and weak, indicating an incompetent and fragile
structure (Figure 4).
The panel is supported by 110 pillars, each spaced
36.5 m by 41.5 m from center to center, at a depth vary-
ing between 240 and 291 meters. The Rock Mass Rating
(RMR) of the immediate roof strata was determined to be
61.31 however, after applying a 10% reduction due to the
conventional BPMM, the RMR dropped to 55.18, under-
scoring the impact of mining practices on rock stability.
The pillars exhibit shale, mudstone, and carbonaceous shale
bands within their height, which introduce weak planes that
potentially compromise the overall stability and strength of
the coal pillars. This investigation into the geological and
structural conditions of Panel No. C‑2 provides a compre-
hensive understanding of the potential challenges in pillar
stability due to the presence of weak bedding planes and
fractured roof strata. The results highlight the importance
of more analysis using empirical and numerical models to
evaluate the stability of the widened and heightened pillars.
This analysis is critical for creating effective safety measures
in underground mining activities.
41
.5
m
36.5
1.2
6 m
Original dip
gallery
Widened
gallery, 6 m
35
.5
m
30.5 m
Level gallery
3.6
6 m
Figure 2. Surface Plan showing the proposed Panel No. C‑2
of Godavarikhani No. 11 Incline Mine to be extracted by CM
Panel C-2
Panel
C-1
Area B Area B
Area A
Figure 3. Proposed widening of galleries for rectangular pillar size of 36.5 m × 41.5 m (average, centre to centre)
C‑1 (Figure 2). Panel No. C‑2 was initially developed using
semi-mechanized conventional Bord and Pillar Mining
Method (BPMM). The development occurred in two dis-
tinct sections: one along the middle horizon and another
along the top section, with the immediate roof consisting
of sandstone.
The field investigation revealed that a significant por-
tion of the panel was initially developed using semi-mech-
anized BPMM, with gallery dimensions of 3.6 m in width
and 2.5 m in height. However, to facilitate CM opera-
tions, the gallery size was later widened to 6 m in width (as
shown in Figure 3) and heightened to 5 m. This expansion,
which exceeded statutory provisions, was permitted by the
Directorate General of Mines Safety (DGMS), India, to
allow sufficient maneuvering space for the CM equipment.
The increased gallery size posed challenges for roof stability,
as the immediate roof of coal and shale was found to be
fractured and weak, indicating an incompetent and fragile
structure (Figure 4).
The panel is supported by 110 pillars, each spaced
36.5 m by 41.5 m from center to center, at a depth vary-
ing between 240 and 291 meters. The Rock Mass Rating
(RMR) of the immediate roof strata was determined to be
61.31 however, after applying a 10% reduction due to the
conventional BPMM, the RMR dropped to 55.18, under-
scoring the impact of mining practices on rock stability.
The pillars exhibit shale, mudstone, and carbonaceous shale
bands within their height, which introduce weak planes that
potentially compromise the overall stability and strength of
the coal pillars. This investigation into the geological and
structural conditions of Panel No. C‑2 provides a compre-
hensive understanding of the potential challenges in pillar
stability due to the presence of weak bedding planes and
fractured roof strata. The results highlight the importance
of more analysis using empirical and numerical models to
evaluate the stability of the widened and heightened pillars.
This analysis is critical for creating effective safety measures
in underground mining activities.
41
.5
m
36.5
1.2
6 m
Original dip
gallery
Widened
gallery, 6 m
35
.5
m
30.5 m
Level gallery
3.6
6 m
Figure 2. Surface Plan showing the proposed Panel No. C‑2
of Godavarikhani No. 11 Incline Mine to be extracted by CM
Panel C-2
Panel
C-1
Area B Area B
Area A
Figure 3. Proposed widening of galleries for rectangular pillar size of 36.5 m × 41.5 m (average, centre to centre)