Research Study on Pillar Design for Vertical Crater Retreat (VCR) Mining

摘要

A 4-year study was conducted of the rock mechanics aspects of two underground hard-rock mine study stopes: (1) Anaconda Minerals Co.'s Carr Fork Mine near Tooele, UT, and (2) Homestake Mining Co.'s Homestake Mine in Lead, SD. 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.