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Laboratory experiment of stemming impact on rock fragmentation by a high explosive
Highlights Ten cylindrical granite specimens were blasted. Stemmed blasts yielded much finer fragmentation than unstemmed blasts. Unstemmed blasts wasted much more explosive energy than unstemmed blasts.
Abstract Ten blasts with cylindrical granite specimens were carried out in four groups with different specific charges and different constraint conditions. All rock specimens came from a granite quarry and they were cylinders with a diameter of 240 mm and a length of 300 mm. Three specific charges—0.2, 0.3 and 0.6 kg/m3 with Research Department Explosive (RDX) as a package charge—were used, and two constraint conditions were tested. In the first constraint condition the rock specimen had a free surface, but a larger steel tube was placed outside the specimen; in the second one the specimen had a free surface and there was no steel tube or other obstacle outside the specimen. Each group included at least one specimen with stemming and at least one without stemming. During blasting, a high-speed camera was used to film the blasting process, and after each blast all fragments including fine materials were collected, sieved and analyzed. The results indicated that: (1) stemmed blasts yielded much better (finer) fragmentation than unstemmed blasts at a constant specific charge, (2) unstemmed blast wasted at least 25% explosive energy in fragmentation, compared with stemmed blasts, and (3) higher specific charge resulted in better fragmentation in either stemmed blasts or unstemmed ones.
Laboratory experiment of stemming impact on rock fragmentation by a high explosive
Highlights Ten cylindrical granite specimens were blasted. Stemmed blasts yielded much finer fragmentation than unstemmed blasts. Unstemmed blasts wasted much more explosive energy than unstemmed blasts.
Abstract Ten blasts with cylindrical granite specimens were carried out in four groups with different specific charges and different constraint conditions. All rock specimens came from a granite quarry and they were cylinders with a diameter of 240 mm and a length of 300 mm. Three specific charges—0.2, 0.3 and 0.6 kg/m3 with Research Department Explosive (RDX) as a package charge—were used, and two constraint conditions were tested. In the first constraint condition the rock specimen had a free surface, but a larger steel tube was placed outside the specimen; in the second one the specimen had a free surface and there was no steel tube or other obstacle outside the specimen. Each group included at least one specimen with stemming and at least one without stemming. During blasting, a high-speed camera was used to film the blasting process, and after each blast all fragments including fine materials were collected, sieved and analyzed. The results indicated that: (1) stemmed blasts yielded much better (finer) fragmentation than unstemmed blasts at a constant specific charge, (2) unstemmed blast wasted at least 25% explosive energy in fragmentation, compared with stemmed blasts, and (3) higher specific charge resulted in better fragmentation in either stemmed blasts or unstemmed ones.
Laboratory experiment of stemming impact on rock fragmentation by a high explosive
Zhang, Zong-Xian (author) / Hou, De-Feng (author) / Guo, Ziru (author) / He, Zhiwei (author)
2019-12-20
Article (Journal)
Electronic Resource
English