Room-and-Pillar Mining in Bump-Prone Conditions and Thin Pillar Mining as a BumpMitigation Technique

摘要

Retreat or pillar recovery mining redistributes the overburden weight onto theadjacent coal pillars in a room-and-pillar section. The additional stress and the resultant energy stored in the remaining pillars can become so great that pillars may bump or violently fail. An investigation at the Gary No. 2 Mine was conducted to examine the effectiveness of the thin pillar mining method for mitigating bump occurrences. Field observations were made and instruments were installed to monitor pillar behavior during extraction. Stress monitoring instruments and roof-to-floor convergence stations were installed in pillars and entries and crosscuts, respectively. Results indicated that high pillar stress concentrations occurred in these bump-prone geologic conditions.