孔壁に設けられた切り欠きによる爆破クラックの制御とそのSB効果
1986 年 1986 巻 373 号 p. 131-138
詳細
1986 年 1986 巻 373 号 p. 131-138
Tunnel blasting causes several undesirable effects, for example, overbreak at the perimeter and damage to or loosening of the remaining rock at the perimeter. Notched blast hole technique is sometimes employed in order to minimize these undesirable effects.
Model blast tests were conducted in order to simulate the propagation of blast cracks from the notched holes. Through the tests, the following conclusions were summarized.
(1) Notching of blast holes can initiate blast cracks from the notch tips.
(2) The fracture plane from the notch tip is rough when the hole is loaded with high explosive detonation. It is smooth when the hole is loaded with low explosive combustion gas pressure.
(3) When the notched holes are used as perimeter blast holes, underbreak can be reduced remarkably.
