In situ Stress at the Lucky Friday Mine (in Four Parts). 3. Reanalysis ofOvercore Measurements from the Star Mine

摘要

U.S. Bureau of Mines researchers reviewed an in situ stress estimate developedfrom measurements of overcore strain taken at test sites on the 7300 and 7500 levels of the Star Mine near Mullan, ID. Although the field measurements of overcoring strain found to be useful, significant deficiencies were found in the stress estimation procedure. A new stress estimate was developed incorporating statistical methods and a greater understanding of doorstopper cell stress concentration factors. Spatial variability of overcore strains and the implications for stress field variability were explored. This analysis will be combined with similar stress estimates developed from overcore measurements and observational evidence of in situ stress orientation to characterize the in situ stress field in the vicinity of the Lucky Friday Mine, also near Mullan, ID.