Smooth blasting with the electronic delay detonator
- Asahi Chemical Industry Co., Ltd. (Japan)
The authors utilized electronic detonators (EDs) to investigate the effect of high detonator delay accuracy on overbreak, remaining rock damage, and surface smoothness, in comparison with that of long-period delay detonators (0.25 sec interval) PDs. The experiments were conducted in a deep mine, in a test site region composed of very hard granodiorite with a seismic wave velocity of about 6.0 km/sec and a uniaxial compressive strength, uniaxial tensile strength, and Young`s modulus of 300 MPa, 12 MPa, and 73 GPa, respectively. The blasting design was for a test tunnel excavation of 8 m{sup 2} in cross section, with an advance per round of 2.5 m. Five rounds were performed, each with a large-hole cut and perimeter holes in a 0.4-m spacing charged with 20-mm-diameter water gel explosive to obtain low charge concentration. EDs were used in the holes on the perimeter of the right half, and PDs were used in all other holes. Following each shot, the cross section was measured by laser to determine amount of overbreak and surface smoothness. In situ seismic prospecting was used to estimate the depth of damage in the remaining rock, and the damage was further investigated by boring into both side walls.
- OSTI ID:
- 398353
- Report Number(s):
- CONF-9502142-; TRN: IM9649%%561
- Resource Relation:
- Conference: 11. annual symposium on explosives and blasting research, Nashville, TN (United States), 5-9 Feb 1995; Other Information: PBD: 1995; Related Information: Is Part Of Proceedings of the eleventh annual symposium on explosives and blasting research; PB: 348 p.
- Country of Publication:
- United States
- Language:
- English
Similar Records
Effects of decoupling and simultaneous detonation on blast vibrations
Hard rock excavation at the CSM/OCRD test site using crater theory and current United States controlled smooth wall blasting practices, June 1982