Abstract

After sealing a portion of or closing an underground room and pillar coal mine, the mined spaces are likely to be filled with water. In many cases, the mine water accumulated in the mined spaces could weaken the remnant mine structures which might lead to their failure in larges areas and subsequent surface subsidence. In some other cases, the hydrostatic pressure associated with the accumulated mine water acts as a supplemental roof supporting force to prevent the occurrence of surface subsidence. The mechanisms for mine water to cause or prevent surface subsidence over inactive room and pillar coal mines are explained and the appropriate mechanical models to assess the mine water effects have been proposed in the paper. One investigated subsidence case over inactive coal mines caused by the failure of water-weakened mine structures and another by water withdrawal are presented. The root causes, subsidence formation process, and subsidence effects of these subsidence events are analyzed.

Keywords: Water; Coal mine; Surface subsidence; Creeping; Cyclic Weathering; Geology