Assessment of near-field blast effect toward optimized drilling-and-blasting in pit wall rock mass

The article presents the scientific research findings on the effect of a borehole charge blast in the near field. The detailed analysis of pit wall damages under massive blasting is performed depending on the rock fracture mechanism. It is found that basic factors to contribute to initiation and opening of fractures in the near field are the high peak particle velocities and post-limiting pressure of gaseous products of explosive detonation. The experimental blasts are described in detail and implemented. The aim of the experimental blasting was to measure PPV directly in rock mass, in the near field of a blasthole charge, and to determine the permeability factor of a separatory slot. The measurement results were processed and analyzed using the Sweden model Holmberg & Persson which allows interpreting and estimating PPV at any point of rock masses. Alongside with PPV, the permeability factor of a separatory slot was determined, which ranged as 52 to 61 % depending on the distance to the slot and on the explosive charge design. The obtained value is reflective of the good quality of cut-back in the pit. The fracture modeling has shown that H & P model is conservative and overestimates the actual level of vibrations. Despite the shortcomings, the model is applicable in drilling-and-blasting pattern design though it needs some calibration using the real-life criteria of rock fracture under the dynamic impact of borehole charge blasting.

Keywords: ultimate pit limit, drilling-and-blasting, blasthole charge, preliminary slotting, peak particle velocity, blast near field, Holmberg & Persson model, modeling.
For citation:

Alenichev I.A., Rakhmanov R.A., Shubin I. L. Assessment of near-field blast effect toward optimized drilling-and-blasting in pit wall rock mass. MIAB. Mining Inf. Anal. Bull. 2020;(4):85-95. [In Russ]. DOI: 10.25018/0236-1493-2020-4-0-85-95.

Acknowledgements:
Issue number: 4
Year: 2020
Page number: 85-95
ISBN: 0236-1493
UDK: 622.235
DOI: 10.25018/0236-1493-2020-4-0-85-95
Article receipt date: 03.02.2020
Date of review receipt: 17.02.2020
Date of the editorial board′s decision on the article′s publishing: 20.03.2020
About authors:

I.A. Alenichev, Cand. Sci. (Eng.), Leading Engineer for Drilling and Blasting, LLC «Polyus Project», 660028, Krasnoyarsk, Russia, e-mail: AlenichevIA@polyusgold.com,
R.A. Rakhmanov, Cand. Sci. (Eng.), Senior Drill and Blast Manager, UK Polyus LLC, 123056, Moscow, Russia, e-mail: RakhmanovRA@polyusgold.com,
I.L. Shubin, Technical Manager (Europe/CIS/N-W Africa), JSC «Davey Bickford Enaex», Russia, e-mail: igor.shubin@daveybickfordenaex.com.

For contacts:

I.A. Alenichev, e-mail: AlenichevIA@polyusgold.com.

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