Controlled Fracture Growth by Blasting While Protecting Damages to Remaining Rock
Rent the article at a discountRent now
* Final gross prices may vary according to local VAT.Get Access
Conventional blasting causes cracks and fractures in the rock. Controlled blasting techniques produce the macrocrack in a desired direction and eliminate microcrack in the remaining rock. Macrocrack development in desired direction is required for extraction of dimensional stone and at the same time there is need to reduce microcrack development in the block and remaining rock. To achieve the objectives, experimental work in the quarries was carried out for separating marble block from the in situ strata as practiced in some of the Indian mines by using detonating cord of 30 to 50 g/m by varying hole spacing, hole diameter, air cushioning, water and sand filled blast-holes. Blasthole notching was carried out. Further, tests were carried out by using various liners inside the blasthole to determine the damages in the extracted block and remaining rock. The designed experimental work was undertaken and rock samples were collected by coring before and after blasting for quantification of microcrack in the rock. P-wave velocity and microscopic studies were conducted for quantification of damages. Experiments were also conducted at laboratory scale for the quantification of damages in single circular and notched holes with variation of stemming and liners. The P-wave velocity close to hole always reduces after blast and in case of NG-based charge and detonating cord it decreases up to 1/3rd. With PVC pipe and paper tube liners decrease is negligible. Thus, by using notched hole with paper tube, decrease in P-wave is minimum indicating least damage.
- Barker, D. B., Fourney, W. L. (1978) Photo elastic investigation of fragmentation mechanism, Part I. Report. University of Maryland, College Park, MD
- Bhandari, S. (1975): Studies on rock fragmentation in blasting. Ph.D. thesis, University of New South Wales, October, 175–182.
- Bhandari, S., Rathore, S. S. (2001): Extraction of marble blocks by controlled blasting techniques-a case study. In: Proc., 10th International Symposium on Mine Planning and Equipment Selection, New Delhi, November 19–21, 295–302.
- Bhandari, S., Rathore, S. S. (2002): Development of macrocrack by blasting while protecting damages to remaining rock. In: Proc., 7th International Symposium on Rock Fragmentation by Blasting (Fragblast-7), Beijing, China, 176–181.
- Brinkmann, J. R. (1987): Separating shock wave and gas expansion breakage mechanism. In: Proc., 2nd International Symposium on Rock Fragmentation by Blasting-FRAGBLAST-2, Keystone, Colorado, August 23–26, 6–15.
- Chiappetta, R. F., Bauer, A., Dally, P. J., Burchell, S. L. (1983): Use of high speed motion picture photography. In: Proc., 1st International Symposium Rock Fragmentation by Blasting-FRAGBLAST-1, Dallas, 258–309.
- Holmberg, R. (1993): Recent development to control rock damage. In: Proc., 4th International Symposium on Rock Fragmentation by Blasting-FRAGBLAST-4 held at Vienna, Austria, July 5–8, 197–200.
- Jiag, J. J. (1996): Study of pre-split blasting using fracture mechanics. In: Proc., 5th International Symposium on Rock Fragmentation by Blasting-FRAGBLAST-5, Montreal/Quebec, Canada, August 25–29, 201–206.
- Olsson, M., Bergqvist, I. (1996): Crack length from explosive in multiple hole blasting. In: Proc., 5th International Symposium on Rock Fragmentation by Blasting-FRAGBLAST-5 Montreal/Quebec, Canada, August 25–29, 187–194.
- Paventi, M., Lizotte, Y., Scoble, M., Mohanty, B. (1996): Measuring rock mass damage in drifting. In: Proc., 5th International Symposium on Rock Fragmentation by Blasting-FRAGBLAST-5 held at Montreal/Quebec, Canada, August 25–29, 131–138.
- Rinehart, J. S. (1971): Fractures and strains generated in jointed and layered masses by explosions. Rev. 1’ Industrial Minerals-Mines, Special No., 146–151.
- Yu, T. R., Vongpaisal, S. (1996): New blast damage vriteria for underground blasting. CIM Bull. March 1996, 139–145.
- Zhang, J. C., Chang, C. (1999): On damage mechanism of micro crack zone in rock blasting and its measurements. In: Proc., 6th, International Symposium for Rock Fragmentation by Blasting. The South African Inst. Of Mining and Metall., Johannesburg, August 8–10, 358–363.
- Controlled Fracture Growth by Blasting While Protecting Damages to Remaining Rock
Rock Mechanics and Rock Engineering
Volume 40, Issue 3 , pp 317-326
- Cover Date
- Print ISSN
- Online ISSN
- Additional Links
- Keywords: Blast damage quantification, blasthole notching, blasthole liners, P-wave velocity.
- Industry Sectors