1. Home
  2. Vol 9, No 3 (2023)
  3. Tahir

Design of Controlled Pre-Split Blasting in a Hydroelectric Construction Project

Younes Tahir, Imad Kadiri, Saïf Ed-dîn Fertahi, Mohammed El Youbi, Rachid Bouferra, Rachid Agounoun, M. Dlimi

Abstract


Geologic conditions and design requirements around upstream Nachtigal Falls, in Cameroon, for the hydroelectric construction project on the Sanaga River dictated close control of blasting procedures with very precise geometry to obtain safe and economical excavation lines. Various techniques of pre-split blasting were used in the initial stage of all major excavations. Hole diameters for pre-splitting were 89 mm, and hole spacing ranged from 0.8 to 1m. Explosive charges varied from 1 to 7 kg per hole, and the detonating cord linear charge ranged from 12 to 60g. The contour blasting technique is aimed at controlling overbreak and improving remaining slope stability. Over-break or over-excavation needs to be controlled since its occurrence compromises the operations in terms of safety (instability in the remaining slope; loosening rocks that increase the risk for operational people; an irregular free face for subsequent blasting); and costs (need for reinforcement of the remaining rock structure through costly sustainment systems; increase in concrete volumes in civil works). This paper discusses in detail the design and field implementation of pre-split blasts successfully carried out to achieve clean vertical walls in moderately dipping, though complexly sheared and jointed gneiss. Based on the results of the experiments, we were able to design a pre-splitting pattern both experimentally and in a very cost-effective manner. It is felt that the methods developed on this project could have useful applications on other major construction projects.

 

Doi: 10.28991/CEJ-2023-09-03-05

Full Text: PDF


Keywords


GNSS Network; Controlled Blasting; Pre-Splitting; Back-Break Control; Fracture Propagation.

References


Paine, R. S., Holmes, D. K., & Clark, H. E. (1962). Controlling Over-break by Pre-splitting. Proceedings of an International Symposium on Mining research, February, 1962, University of Missouri, Columbia, United States.

Singh, P. K., Roy, M. P., & Paswan, R. K. (2014). Controlled blasting for long term stability of pit-walls. International Journal of Rock Mechanics and Mining Sciences, 70, 388–399. doi:10.1016/j.ijrmms.2014.05.006.

Kadiri, I., Tahir, Y., Iken, O., Fertahi, S. E. D., & Agounoun, R. (2019). Experimental and statistical analysis of blast-induced ground vibrations (BIGV) prediction in Senegal’s quarry. Studia Geotechnica et Mechanica, 41(4), 231–246. doi:10.2478/sgem-2019-0025.

Paurush, P., Rai, P., & Sharma, S. K. (2021). Selection of Blasting Design Parameters Affecting Peak Particle Velocity—a Case Study. Mining, Metallurgy and Exploration, 38(3), 1435–1447. doi:10.1007/s42461-021-00408-9.

Calder, P. N., & Tuomi, J. N. (1980). Control Blasting At Sherman Mine. Proceedings of the 6th Annual Conference on Explosives and Blasting Technique, Montville, Australia.

Lu, W., Chen, M., Geng, X., Shu, D., & Zhou, C. (2012). A study of excavation sequence and contour blasting method for underground powerhouses of hydropower stations. Tunnelling and Underground Space Technology, 29(29), 31–39. doi:10.1016/j.tust.2011.12.008.

Zhang, Z., Zhang, N., Shimada, H., Sasaoka, T., & Wahyudi, S. (2017). Optimization of hard roof structure over retained Goaf-side Gateroad by pre-split blasting technology. International Journal of Rock Mechanics and Mining Sciences, 100, 330–337. doi:10.1016/j.ijrmms.2017.04.007.

International Society of Explosive Engineers (ISEE). (2020). ISEE Blaster’s Handbook (18th Ed.). International Society of Explosives Engineers, Cleveland, United States.

Onederra, I. A., Catalan, A., & Quidim, J. (2016). Evaluating pre-split performance through direct measurements of near field acceleration, particle velocity and gas pressure. Mining Technology, 1–11. doi:10.1179/1743286315y.0000000023.

Konya, A.J. & Konya, C.J. (2022). The Development of Pressure to Young Modulus Models for Precision Pre-split Blasting. European Federation of Explosives Engineers, February 2021, 30-39.

Xu, M. B., & Peng, D. H. (2008). Parameter optimization of the slope pre-splitting blasting. Baozha Yu Chongji / Explosion and Shock Waves, 28(4), 355–359.

Dai, J. (2005). Study on parameters of directional-split blasting based on protecting effectively remaining rock. Liaoning Gongcheng Jishu Daxue Xuebao/Journal of Liaoning Technical University (China), 24(3), 369-371.

Monjezi, M., Amini Khoshalan, H., & Yazdian Varjani, A. (2011). Optimization of Open pit Blast Parameters using Genetic Algorithm. International Journal of Rock Mechanics and Mining Sciences, 48(5), 864–869. doi:10.1016/j.ijrmms.2011.04.005.

Hao, H., Wu, C., & Seah, C. C. (2002). Numerical analysis of blast-induced stress waves in a rock mass with anisotropic continuum damage models Part 2: Stochastic approach. Rock Mechanics and Rock Engineering, 35(2), 95–108. doi:10.1007/s006030200013.

Wang, Z., Wu, G., & Zhou, L. (2022). Optimization of pre-splitting blasting hole network parameters and engineering applications in open pit mine. Applied Sciences (Switzerland), 12(10), 4930. doi:10.3390/app12104930.

Eades, R. Q., & Perry, K. (2019). Understanding the connection between blasting and high wall stability. International Journal of Mining Science and Technology, 29(1), 99–103. doi:10.1016/j.ijmst.2018.11.016.

McKenzie, C., & Holley, K. (2004). A study of damage profiles behind blasts. Proceedings of the 30th Annual Conference on Explosives and Blasting Technique, 1-4 February, 2004, New Orleans, United States.

Saharan, M. R., & Mitri, H. S. (2008). Numerical procedure for dynamic simulation of discrete fractures due to blasting. Rock Mechanics and Rock Engineering, 41(5), 641–670. doi:10.1007/s00603-007-0136-9.

Kadiri, I., Tahir, Y., Fertahi, S. ed D., Iken, O., Dlimi, M., Agounoun, R., & Sbai, K. (2020). Measurement and 2d axisymmetric modeling of mining blast-induced ground vibrations. Indian Geotechnical Journal, 50(1), 96–116. doi:10.1007/s40098-019-00388-0.

Hu, Y., Lu, W., Chen, M., Yan, P., & Yang, J. (2014). Comparison of blast-induced damage between presplit and smooth blasting of high rock slope. Rock Mechanics and Rock Engineering, 47(4), 1307–1320. doi:10.1007/s00603-013-0475-7.

Dumont, J. F. (1986). Identification by remote sensing of the Sanaga accident (Cameroon). Its position in the context of the great accidents of Central Africa and the northern limit of the Congolese Craton. Géodynamique, 1, 13-19. (In French).

Olivry, J. C. (1986). Rivers and streams of Cameroon. MESRES-ORSTOM: Paris, France.

Feng, X. T., & Hudson, J. A. (2010). Specifying the information required for rock mechanics modelling and rock engineering design. International Journal of Rock Mechanics and Mining Sciences, 47(2), 179–194. doi:10.1016/j.ijrmms.2009.12.009.

Carlos, L. J., Emilio, L. J., Francisco, J. A. C., & Yvonne Visser de, R. (2017). Drilling and Blasting of Rocks. Routledge, London, Unite Kingdom. doi:10.1201/9781315141435.

Chiappetta RF. (2001). The importance of pre-splitting and field controls to maintain stable high walls, and eliminate coal damage and overbreak. Tenth high-tech seminar on State of the art, blasting technology, instrumentation, and explosives application, GI-48, 22–26 July, 2001, Nashville, United States.


Full Text: PDF

DOI: 10.28991/CEJ-2023-09-03-05

Refbacks

  • There are currently no refbacks.


Bookmark and Share


Copyright (c) 2023 YOUNES TAHIR

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
x
Message