Pillar strength in underground stone mines in the United States.
Esterhuizen-GS; Dolinar-DR; Ellenberger-JL
Int J Rock Mech Min Sci 2011 Jan; 48(1):42-50
Stone mines in the Eastern and Midwestern United States make use of the room-and-pillar method of mining to extract relatively flat-laying sedimentary formations. A survey of pillar performance was carried out to identify potential modes of instability. Pillars were found to have been successful in providing support to the overburden, but a small number of individual failed pillars were observed. Failure of the pillars was observed to be related to spalling of the hard brittle rocks, shearing along pre-existing angular discontinuities or progressive extrusion of soft infill materials on bedding planes. A method of estimating the pillar strength and selecting a safety factor for design was developed based on observations of stable and failed pillars, supplemented by numerical models. The developed pillar strength equation can be used to design stable stone mine pillars provided the rock conditions are similar to those included in the study.
Mining-industry; Underground-mining; Mine-shafts; Ground-control; Ground-stability; Stone-mines; Room-and-pillar-mining; Rock-mechanics; Failure-analysis; Structural-analysis;
Author Keywords: Pillar design; Pillar strength; Stone mines; Limestone; Room-and-pillar
G. S. Esterhuizen, National Institute for Occupational Safety and Health, P.O. Box 18070, Pittsburgh, PA 15236 USA
International Journal of Rock Mechanics and Mining Sciences