Caulking of Goafs Formed by Cave-in Mining and its Impact on Surface Subsidence in Hard Coal Mines

Abstract

The impact of caulking of goafs after mining exploitation of a hard coal seam with caving is expressed as the change in value of a a exploitation coefficient which, as defined, is the quotient of the maximum reduction in the surface height of a complete or incomplete trough to the thickness of the exploited seam. The basis for determining the value of the exploitation coefficient was geological and mining data combined with the results of the measurement of subsidence on the surface – measuring line 1222-1301 – of the ruda mine. There, mining was carried out between 2005 and 2019, with a transverse longwall system and the caulking of goafs. The research team used two methods to determine the impact of the caulking applied in the goafs on the value of the exploitation coefficient. in the first method the goafs are filled evenly along the whole longwall, and in the second method unevenly and on a quarterly basis. The determination of the values of the exploitation coefficients for selected measuring points was preceded by the determination of the parameters of the knothe-Budryk theory, which was further developed by J. Białek. The obtained dependencies are linear and the values of the correlation coefficients fall between –0.684 and –0.702, which should be considered satisfactory in terms of experimental data. it is possible to reduce the value of the exploitation coefficient by caulking the goafs by about 18%, when filling the goafs to 0.26% of the height of the active longwall.