Puff 'n tuff, a residual stress-gas fracturing experiment. [Chemical underground explosion]
Subsequent to the dynamic effects from a contained explosion in rock there remains a residual stress field around the cavity. This field is associated with the dynamic rebound of the cavity. Calculations show that the radial component of the residual stress field is compressive, exhibits a maximum near the cavity, and decays to the in situ stress value. The tangential component shows a greater compressive value than the radial component, decays to a value below the in situ stress, and subsequently rises up to the in situ value. This residual stress effect is believed to be responsible for containment of underground explosions, for calculations show residual cavity pressures to be greater than the sum of the tensile strength of the rock and the overburden stress. A chemical explosion was conducted in an ash fall tuff at a depth of 425 meters and near a tunnel complex. The latter allows subsequent mineback. The experiment involved a 116 kg TNT sphere and a 0.2 meter diameter hole extending radially in the tuff from the emplaced charge. In effect, this provided an opening through the explosively formed residual stress field. Based on this experiment, an inexpensive fracturing technique for tight geologic formations is suggested.
- Research Organization:
- Sandia Labs., Albuquerque, N.Mex. (USA)
- DOE Contract Number:
- EY-76-C-04-0789
- OSTI ID:
- 5088709
- Report Number(s):
- SAND-78-0394C; CONF-780509-6
- Resource Relation:
- Conference: 19. symposium on rock mechanics, Lake Tahoe, NV, USA, 1 May 1978; Other Information: Portions of document are illegible
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
CAVITIES
STRESS ANALYSIS
CHEMICAL EXPLOSIONS
UNDERGROUND EXPLOSIONS
TUFF
EXPLOSIVE FRACTURING
CONTAINED EXPLOSIONS
MECHANICAL PROPERTIES
ROCK MECHANICS
COMMINUTION
EXPLOSIONS
FRACTURING
IGNEOUS ROCKS
ROCKS
580300* - Mineralogy
Petrology
& Rock Mechanics- (-1989)
450100 - Military Technology
Weaponry
& National Defense- Chemical Explosions & Explosives