YIELD PILLAR DESIGN AT DEPTH BASED ON REVIEW OF CASE HISTORIES

摘要

Yield pillars are used in deep coal longwall mines, where thedepth of cover is so great that a conventional chain pillar design tendsto be unsuccessful. The design of yield pillars in deep U.S. mines hasbeen based mainly on experience, pressure arch theories, numericalmodeling, and empirical methods that originated in the eastern U.S.coal mines. This paper offers field experience based guidelines for thedesign of yield pillars through analysis and evaluation of numerouscase histories.Case histories of yield pillar applications were collated andcritically reviewed to identify trends in data that can be used toformulate the design guidelines. Convincing trends observed in thecase of successful case histories indicate that yield pillars shouldhave a width to height ratio in the range from 2.8 to 6.0, a stabilityfactor during development between 0.4 and 0.6, and shed between94% to 98% of the cover and abutment load, as provided by the Carr-Wilson (1982) method. Also, yield pillars should be utilized in coalmines only where the roof and floor rock have a CMRR rating of 50 orbetter.