Mining exploitation of hard coal seams by galleries and surface deformations

several mines, leaving pillars of coal between roadways. This is
particularly applicable in the old mines where the residue of hard
coal deposits, left in the protective pillars of mine shafts or other
facilities, is exploited. The article presents the mining process
carried out with a single gallery in three seams and grouped in plots
and consequent surface deformations. Extraction galleries were 5.6
m wide and 3.8-4.3 m high. Coal pillars with an average width of 12
m were left in plots between galleries. Decommissioning of
galleries was carried out by filling them with hydraulic backfill
from waste (dust) from the power plant. The width of the coal
pillars was determined depending on the level of protection required
to secure objects on the surface properly.
In seams, where single galleries were used, the exploitation factor
ranged from 0.05 to 0.25 (!), and 0.21. above the extraction plots.
The value of exploitation factor, as well as rock mass (tgβ as in
Knothe-Budryk theory), is significantly influenced by remains (old
excavations) that were activated by new exploitation. The obtained
results were confronted with the Polish and world underground coal
mines.