Hole Springing.
Abstract
Hole springing tests were executed during the period July 1969 through September 1971 in five different media - coral, clay shale, weathered granite, unweathered granite, and interbedded sandstone and shale to investigate the feasibility of constructing cratering charge emplacement cavities. Hole springing is defined as enlarging the bottom of a drill hole by successive detonations of small explosive charges. It was found that it is most effective in compressible media, such as clay shale, for creating charge cavities. However, to be effective the springing charge must be kept small and the number of detonations in any one hole must be limited. Even when both of these criteria are met there will be some percentage of hole loss. Therefore, when an explosive excavation design depends on a precise cratering charge location and size, hole spring does not appear to be economical or feasible. However, hole springing can be effectively used for increasing the size of charge which can be placed in a quarrying or mounding borehole. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1972
- Accession Number
- AD0755097
Entities
People
- Richard H. Gillespie