Science and Technology of Energetic Materials

Vol.65, No.6 (2004)

Research paper

Fly-rock incidents by blasting at three quarries
Katsumi Noguchi


There were six quarry sites owned in separate companies, which were lined together on a shore side in the north of Kyusyu in Japan. During 1998 to 2000, fly-rock incidents by blasting occurred at three quarries in there. Even worse, those occurred at a time continuously every year, and worse still, two of those were located next to each other. There were some site facilities within each quarry site concerned and some offices with the parking space, a factory or a shop, etc. around them. Fly-rocks by blasting injured and damaged to a blaster in charge on evacuation on the site and a pickup truck stopping at his side, a factory employee driving a car and it's body, the roof of a factory building, a truck parking at a the shop and etc.

An author got an opportunity to inspect then blasting situation the later on-site condition in response to the request from prefectural administration authorities as well as each quarry manager. The inspection for each case found that whole the round was of over-charge but a certain hole or the part on the blast site became a source origin of the fly-rock, that seems to have involved a sharp change in condition on the site deeply, that is, local existence of some poor rock-quality with dense joints or widely open fractures, some hole filled with water, some hole-deviation due to uneven crest face, an irregularity of blast face and etc.

In order to minimize the danger of fly-rock, needless to say, it is important that any change in such the condition is caught sharply on the blast site and suitable means (with some precaution) are taken certainly depending on the local change. However, for that, blasting should be done with room sufficiently, and it will be necessary that a mutual understanding and a close cooperation relation between a person in charge of blasting work and one in charge of subsequent loading and hauling work etc. will be required. And above all, the quarry manager's recognition about that seems indispensable.

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