Numerical modelling results show that the response characteristics of transient electromagnetic method of high resistivity
goaf are weaker than that of low resistivity
goaf.
Drilling log table of anomaly YC7 in No.80101 workface Drilling Parameter Location Log Azimuth Dip Dcplij Number ([degrees]) ([degrees]) (m) H19-1 313 37 129 H19-2 277 46 125 No.18 H19-3 221 41 130 drilling field of H19-4 136 157 No.80101 H19-5 237 -1 141 return airway H19-6 221 1 133 H19-7 229 -10 130 H19-S1 238 35 111 H19-S2 308 30 156 Final Hole Location Position Hydrology 115m to 4# water yield 8[m.sup.3]/h at 60m 90m to 4#
goaf water yield 30[m.sup.3]/h from final hole No.18 95m to 4#
goaf water yield 35[m.sup.3]/h from drilling final hole field of 99m to 4#
goaf none No.80101 Floor of 8# none return airway scam Floor of 8# none scam Floor of 8# none scam 4# scam water yield 3[m.sup.3]/h.
(3) The degree of pollution risk to the groundwater environment when using the weathered coal gangue as a filling for the
goaf area is obviously higher than that when using the fresh gangue.
Backfill mining is to fill the filling materials into
goaf of working face in order to control overburden strata caving and surface subsidence in
goaf [26,27].
In zone B, bedrock that was deformed after bedrock stratification in zone A, fully transfers its weight into the
goaf, and stratification occurs in the next "packet" of the roof bedrock.
It is a way to place the gob side roof of the roadway with manpower and shorten the spacing in between the
goaf roadway, thereby solving the problems of methane accumulation in the upper corner, air leak on the work face, and great pressure in the supporting roadway.
One of the most important problems occurring during ventilation of longwall headings in hard coal mining is an air migration of air through the
goaf with caving of these headings [1-3].
The strata near the fault rotate to the
goaf because of the effect of the fault and its dip angle.
Goaf filled with water is the common source of water inrush in the roadway.