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Research Study on Pillar Design for Vertical Crater Retreat (VCR) Mining.
NTIS: PB/86-210960 :233 pages
A 4-year study was conducted of the rock mechanics aspects of two underground hard-rock mine study stopes: (1) Anaconda Minerals Company's Carr Fork Mine near Tooele, Utah, and (2) Homestake Mining Company's Homestake Mine in Lead, South Dakota. Large-diameter (6 1/2-in) blastholes were an integral part of the stoping method at each mine. A true vertical crater retreat (VCR) method was used at the Homestake Mine, while a vertical bench mining method (VBM) was used at the Carr Fork Mine. Since there are no personnel in a VCR or VBM stope, all ground control including dimensioning of stopes and pillars and the layout of cable bolt assays or other artificial support must be done in advance of production blasting. Accordingly, the objective of the research study was the establishment of a procedure for optimizing stope and pillar sizes. The approach taken in each case was a combination of mine measurements of the study stope response to mining, laboratory testing for rock properties and in situ stress measurements of the premining stress field, and theoretical calculations of the study stope response to mining. All calculations were done with the Utah-II finite element computer program. Simulation of the blasting sequence gave a correlation of 0.88 Between measured and calculated extensometer readings (incremental relative displacement) at the carr fork mine. A correlation of 0.84 Was obtained at the Homestake mine. The calibrated model was then used in parametric studies of alternative design layouts.
CP; Final Contract Report;
NTIS Accession No.
Univ. of Utah
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division