The effect of the seam slopes on the strata behavior in the longwall coal mines using numerical modeling

proper control and prediction of the roof behavior in the gob area.
Thus, the safety and continuity of mining can be guaranteed by
recognizing the roof seam behavior and determining the time of
roof fall (first fall and periodic fall). Due to the Middle East tectonic
conditions, the coal seams in Iran are usually inclined, so studying
the seam behavior and face stability in different slopes in
underground mining is necessary. In this research, four different
block models were simulated to investigate the roof and face
behaviors in the 0-, 5-, 10-, and 15-degree slopes using the
FLAC3D software. The validation of these models is based on the
simulation of the E3 panel of the Tabas Parvade coal mine. Based
on the numerical modeling results, the values for the first roof
weighting effect interval (FRWEI) in the 0-, 5-, 10-, and 15-degree
slopes were calculated to be equal to 26, 29.09, 31.38, and 36 m,
respectively. According to these results, the gob roof displacement
decreased by increasing the seam slope, and the roof stability time
increased. Also, the instability risk of the face and the roof above it
was reduced by increasing the seam slope.