Full Length Article
An empirical approach for predicting burden velocities in rock blasting

https://doi.org/10.1016/j.jrmge.2021.04.004Get rights and content
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Abstract

An analytical relation between burden velocity and ratio of burden to blasthole diameter is developed in this paper. This relation is found to be consistent with the measured burden velocities of all 37 full-scale blasts found from published articles. These blasts include single-hole blasts, multi-hole blasts, and simultaneously-initiated blasts with various borehole diameters such as 64 mm, 76 mm, 92 mm, 115 mm, 142 mm and 310 mm. All boreholes were fully charged. The agreement between measured and calculated burden velocities demonstrates that this relation can be used to predict the burden velocity of a wide range of full-scale blast with fully-coupled explosive charge and help to determine a correct delay time between adjacent holes or rows in various full-scale blasts involved in tunnelling (or drifting), surface and underground mining production blasts and underground opening slot blasts. In addition, this theoretical relation is found to agree with the measured burden velocities of 9 laboratory small-scale blasts to a certain extent. To predict the burden velocity of a small-scale blast, a further study or modification to the relation is necessary by using more small-scale blasts in the future.

Keywords

Burden velocity
Rock blasting
Kinetic energy
Delay time
Tunnelling
Mining

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Dr. Zong-Xian Zhang is a Professor at the University of Oulu, Finland. He received his PhD degree from the Luleå University of Technology, Sweden in 2001, MSc degree from the University of Science and Technology Beijing in 1986 and BSc degree from Xi’an University of Architecture and Technology in China in 1982. Since the 1990s, he has conducted a series of laboratory studies on the effects of loading rate and high temperature on rock fracture, performed field measurements on excavation-caused cracks in rock mass and on cutter forces and cutter temperature of a boring machine, and carried out a number of small-scale rock blasts aiming to understand the mechanism of rock fracture and fragmentation by blasting. From 2002 to 2013, he worked at a mining company LKAB and developed several technical methods for increasing ore recovery ratio, improving mining safety and reducing blast-induced ground vibrations. All the methods have been proved to be successful not only in the LKAB’s Malmberget mine but also in other mines outside the LKAB. In recent years, his research has been expanded to rock mass evaluation, deep mining technology and muography’s applications to mining and rock engineering.

Peer review under responsibility of Institute of Rock and Soil Mechanics, Chinese Academy of Sciences.

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