Relationship of the discontinuities and the rock blasting results


  • S. Yahyaoui
  • A. Hafsaoui
  • A. Aissi
  • A. Benselhoub
Keywords: Fragmentation, model rock blasting, discontinuities, rock mass, bench blasting

Abstract

The Geological discontinuities such as joint are the most common discontinuities present in the rock mass. A model scale study was carried out to evaluate the effect of the joints on rock blasting. Single hole tests at three selected burdens (optimum, less than optimum and more than optimum) were done on six different joint orientations. The joint orientation angles were 0°, 30°, 60°, 90°, 120° and 150° rotating in anticlockwise direction from the floor of the bench in a plane perpendicular to the free face. Bench models of dimensions 515x335x215 mm with a bench height of 50 mm were prepared by binding sandstone slabs of 25 mm thickness with an adhesive. The models were blasted by n°6 electric detonators. The dynamic and static properties of sandstone are given. The bench crater formed and the fragmentation produced were predominantly influenced by the position of charge with respect to the joint orientation. Severe toes were noticed in models with vertical joints and with joints dipping away from the face. Over breaks were observed in horizontally bedded models and in models with joints dipping towards the free face. Over breaks were observed in horizontally bedded models and in models with joints dipping towards the free face. The size of the broken fragments at 20 mm burden was found to be finer than the fragments obtained at 30 mm and 40 mm burdens for all joint orientations except vertical.

Author Biographies

S. Yahyaoui
Badji Mokhtar University
A. Hafsaoui
Badji Mokhtar University
A. Aissi
Ecole Nationale Supérieure des Mines et Métallurgie
A. Benselhoub
State Agrarian and Economic University

References

1. Ash, R.L. 1961. Drill Pattern and Initiation-Timing Relationships of Multiple Hole Blasting, Quarterly, Colorado School of Mines, Vol. 56, 1, 309-324.
2. Dick, R.A., Olson, J.J. 1972. Choosing of proper Borehole Size for Bench Blasting, Mining Engineering, Vol. 24, 3, 40-46.
3. Kim, S. J. 2010. An Experimental Investigation of the Effect of Blasting on the Impact Breakage of Rocks. Kingston, Ontario, Canada: The Robert M. Buchan Department of Mining, Queen's University, (Master Thesis).
4. Ash, R.L. 1973. The Influence of Geological Discontinuities on Rock Blasting, Ph.D. Thesis, University of Missouri Rolla. 87 pp., 2.
5. Hafsaoui, A., Talhi, K. 2009. Influence of joint direction and position of explosive charge on fragmentation. Arabian Journal for Science and Engineering, Vol. 34, 2A., 125-132.
6. Kolsky, H. 1953. Stress Waves in Solids, Dover Publications, Inc. New York. 10014, Science Education. Volume 52, Issue 5, Inc. 213 p.
7. Goldsmith, V.. Pulse Propagation in Rocks, Proceedings, 8th Symposium on Rock Mechanics, New York, pp. 523-537.(1967)
8. Hafsaoui, A., Talhi, K. 2011. Instrumented Model Rock Blasting.Journal of Testing and Evaluation.Vol. 39, Issue 5, 181-187.
9. Belland, J.M. 1968. Structure as a Control in Rock Fragmentation Coal Lake Iron Ore Deposited, The Canadian Mining and Metallurgical Bulletin, Vol. 59, 647, 323-328.
10. Talhi, K., Bensaker, B. 2003. Design of a model blasting system to measure peak p-wave stress, Soil Dynamics and Earthquake Engineering, Vol. 23, Issue 6, 513-519.
11. Gnirk, P.F., Pfleider, E.D. 1968. On the Correlation Between Explosive Crater Formation and Rock Properties, Proceedings, 9th Symposium on Rock Mechanics, Colorado School of Mines, 321-345.
12. Larson, W.C., Pugleise, J.M. 1974. Effects of Jointing and bedding Separation on Limestone Breakage at Reduced Scale, R.I 7863, U.S. Bureau of Mines. 1-13.
13. Bhandari, S. 1974. Blasting in Non-Homogeneous Rocks, Australian Mining, Vol. 66, 5, 43-48.
14. Singh, D.P., Saluja, S.S., Rao, Y.V.A. 1980. A Laboratory Study of Effects of Joints on Rock Fragmentation, Proceedings, 21stU.S. Rock Mechanics Symposium, University of Missouri Rolls.
15. Wild, H.W. 1977. Geology and Blasting in Open pits, Mining Magazine, March, 1-227.
16. Bjarnholt, G., Skalare, H. 1981. Instrumented Rock Blasting – Initial experiments in Concrete blocks, SveDeFo Stockholm, report DS 1981 : 16, (in Swedish).
17. Johnson, J.B. 1962. Small-scale blasting in mortar. U.S. Dept. of the Interior, Bureau of Mines. 1-22.
18. Haller, H.F., Pattison, H.C., Shimizu, B. 1972. Inter-Relationship of In-situ Rock Properties, A.R.P.A. Order 1579, California.
19. Smith, N.S. 1976. Burden-Rock Stiffness and Its Effect on Fragmentation in Bench Blasting, Ph.D. Thesis, University of Missouri Rolla.
20. Langefors, V. 1959. Calculations of Charge and Scale Model Trials, Quarterly, Colorado School of Mines, Vol. 54, 3, 219-249.
21. Just, G.D., Henderson, D.S. 1971. Model Studies of Fragmentation by Explosives, Proceedings, 1st Australian and Newzeland Conference on Geomechanics, Melbrone, Vol.1, 238-245.
22. Martin, C.W., Murphy, G. 1963. Prediction of Fracture Due to explosives, Engn. Mech. Div. A.S.C.E., Vol. 89, 133-150.
23. Da Gama, C.D. 1970. Laboratory Studies of Comminution in Rock Blasting, M.S. Thesis, University of Minnesota.
24. Saran, S. 1981. A Study of Spacing-Burden Ratio on Rock Fragmentation by Blasting, B.Tech. Project, Banaras Hindu University.
25. Heywoud, H., Pryros, E., J. Applied of sizing analysis to mill practice, Trans. I.M.M., Vol. 55, pp. 405-425.
26. Pryors, E.J. 1965. Mineral Processing, Elsvica Publishing Co. Ltd., London, 150-151.
27. Bond, F.C., and Whitney, B.B. 1959. The Work Index in Blasting, Quarterly Colorado School of Mines, Vol. 54, 77-82.
28. Henderson, D.S. 1971. Model Studies of Fragmentation by Concentrated and Linear Explosive. Charges, M. Eng. Sc. Thesis, University of Queesland..
29. Just, G.D. 1973, The Application of size Equations to Rock Breakage by Explosives, Proceedings, National Symposium on Rock Fragmentation, Adlaide, 18-23.
30. Dick, R.A., Fletcher, L.R., D'Andrea, D.V. 1973. A Study of Fragmentation from Bench Blasting in Limestone at a Reduced Scale, R.I. 7704, U.S. Bureau of Mines.
31. Denoual, C., Hild., F. 2002. Dynamic Fragmentation of Brittle Solids: a Multi-Scale Model. Eur. J. Mech.A/Solids,vol. 21, 1, 105–120.
Published
2018-03-30
How to Cite
Yahyaoui, S., Hafsaoui, A., Aissi, A., & Benselhoub, A. (2018). Relationship of the discontinuities and the rock blasting results. Journal of Geology, Geography and Geoecology, 26(1), 208-218. https://doi.org/https://doi.org/10.15421/111821