Mine subsidence effects on a pressurized natural gas pipeline : Hucka, V J; Blair, C K; Kimball, E P Min EngngV38, N10, Oct 1986, P980–984

Abstract

A 0.5 m (20 in) diameter high pressure natural gas pipeline crosses over a coal mine located in Central Utah. Ground movement induced by the mining operation could possibly place excessive strain on the pipeline causing it to rupture. The mining operation extracts coal from two seams using the room and pillar method. The seams are situated one on top of the other and both lie directly under the pipeline. At present, only the upper seam is being mined beneath the pipeline. However, in the future, the mining operation of the lower seam will also affect the pipeline. As would be expected, mining of both coal seams causes surface subsidence. This is especially true when the pillars are extracted during retreat. This subsidence can be defined as the vertical movement of surface points within a subsidence trough above the coal seam(s). The pipeline may fail since it is not designed to deflect and telescope as the surface undergoes curvature and horizontal strain. Subsidence caused by underground coal mines depends, inter alia, on the mining method, lithological composition of the strata overlaying the coal seam, the presence of geological structures, the horizontal and vertical dimensions of the mine workings, etc.