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Shock Wave Interactions in Rock Blasting: the Use of Short Delays to Improve Fragmentation in Model-Scale

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Abstract

A series of detailed small-scale tests have been made to investigate the use of short delays to promote better fragmentation caused by shock wave interactions. The block design had a size of 650/660 × 205 × 300 mm (L × W × H) and two rows with five Ø 10-mm blastholes in each row. The spacing (S) and burden (B) were 110 and 70 mm, respectively, giving an S/B ratio of 1.6. The results showed no distinct differences or high improvements of the fragmentation when the delays were in the time range of interactions compared with no shock wave interactions. The decrease of x 50 (mean size) was around 20 % at a delay time ~1.1 ms/m burden compared with longer delays like 2 ms/m. A statistical analysis of the results has been made to evaluate the minimum at short delays and it is not significant.

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Acknowledgments

The work has been financed by HLRC, the Hjalmar Lundbohm Research Centre at Luleå University under the project ‘Optimized blasting of SLC rounds through simulations’. The authors also wish to acknowledge the help of Swebrec researches Ulf Nyberg and Håkan Hansson in designing and performing the blasting tests. The accredited road lab, Väglaboratoriet i Norr AB are gratefully thanked for letting us use their professional sieving equipment and procedures. The authors also wish to acknowledge Dr Frédéric Vanbrabant for supplying data about his approach and discussions about it. Prof José Sanchidrián of ETSI Minas at the Politecnico de Madrid discussed the statistical evaluation of the fragmentation data with us. A final acknowledgement is given to Dr. Dane Blair whose constructive criticism and review of our manuscript has helped make it a better paper.

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  1. Rock Mechanics and Rock Engineering, Luleå University of Technology, Luleå, Sweden

    Daniel Johansson

  2. Swebrec, Swedish Blasting Research Centre at Luleå University of Technology, Luleå, Sweden

    Finn Ouchterlony

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  1. Daniel Johansson
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  2. Finn Ouchterlony
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Correspondence to Daniel Johansson.

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Johansson, D., Ouchterlony, F. Shock Wave Interactions in Rock Blasting: the Use of Short Delays to Improve Fragmentation in Model-Scale. Rock Mech Rock Eng 46, 1–18 (2013). https://doi.org/10.1007/s00603-012-0249-7

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