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By Dale Preece, Stephen Chung, D. Scott Scovira

The DMC_BLAST (Distinct Motion Code) has been developed to model rock motion and displacement during the gas expansion phase after the detonation of an explosive in a borehole. Recently, a designated delay firing order algorithm was written into the DMC_BLAST code. The model can now be used to analyze rock mass displacement for a V-cut, center opening, or sinking cut initiation sequences. This new feature allows the investigation of the effects of delay firing order on rock displacement when blasting complex inter-bedded and ore-waste structures. The model provides important ground movement and mixing indicators for dilution control in surface gold mining relative to the initiation sequences employed. Echelon blasts as compared to center opening type blasts show differences in their internal muckpile displacement. These displacement differences can be important to operations that mine narrow strike driven ore bodies. The model also has applications to through coal seam blasting and demonstrates that down-dip blasting is a better alternative than up-dip blasting. There is less disturbance to the dipping coal seam and less mixing of the rock and the coal.

Jan 1, 2000

By Eric Roller, Elliott Giles

All flyrock incidents have the potential to result in injuries or fatalities that can result in loss of company reputation, license to operate with clients, and bear the exposure to high cost liability. From 2007 to 2009,one NA Quarry and Construction Business experienced a series of flyrock incidents. In the spring of 2009, this business declared that the frequency and severity of Flyrock Incidents had reached an unacceptable level. A Flyrock Elimination Program was launched.

Jan 1, 2012

By Leslie Taylor, W. Fourney, Uli Leiste

This paper presents the results from a series of tests conducted to investigate the total vertical impulse delivered to a target plate by a buried explosive charge. The tests were conducted at a very small scale but previous work has shown that small scale testing can predict impulse applied to plates in full scale. Non-deforming plates were used to determine the change in impulse delivered to targets as a result of changes in standoff distance and burial depth changes.

Jan 1, 2009

By Jung-Hoon Ryu, Chang-Ha Ryu, Byung Hee Choi, Yang-Kyun Kim

Control of overbreak in tunnel blasting is one of the key factors affecting the construction expenses as well as safety. Overbreak causes an increase in the cost of construction by requiring an additional amount of shotcrete. In addition, blast damage to the final rock face may cause instability and rock fall hazards. For these reasons, controlled blasting is an indispensable routine in tunnel excavation in order to get a smooth face and to reduce damage to the final wall. We have experienced a very poor quality of excavation depending on the tunneling sites although a similar design of controlled blasting technique was applied. Field experiments over 40 rounds were carried out to investigate the cause of the poor results in tunnel blasting. In this paper, discussed are the parameters affecting the overbreak and some findings from the field experiments. Overbreak could be controlled considerably by adjusting some parameters before the efforts of developing a new blasting method.

Jan 1, 2004

By Detlef Sulzer, Winfried Rosenstock

"At the end of this century a great breakthrough in the field of blasting technology is finally going tobecome reality. That, in the true sense of the word, is the long expected and desired “HighTechnology Blasting”. So far trials have been carried out in Australia, Africa and Europe with remarkable results, that have been predicted by the authors. As a result, significant reductions of explosives and drilling expenditure are emerging for the future."

Jan 1, 1999

By D Linn Coursen

Detonation propagates in the subject blasting agent at about 2.7 km/sec when it is heavily primed but explosion propagates in it at only about 0.43 km/sec when it is lightly primed. When propagating at 0.43 km/sec, it produces a borehole pressure that is slightly less than 1 kb, but no yellow fumes or other sign of incomplete reaction. It is a pumped AN/emulsion blend to which additional water is added by circumferential injection at the inlet of the hose through which it is pumped.

Jan 1, 1994

By Dale S. Preece, J Paul Tidman, Stephen H. Chung

A discrete element computer program named DMC_BLAST (Distinct Motion Code) has been under development since 1987 for modeling rock blasting (Preece & Taylor, 1989). This program employs explicit time integration and uses spherical or cylindrical elements that are represented as circles in 2-D. DMC_BLAST calculations compare favorably with data from actual bench blasts (Preece et al, 1993).

Jan 1, 1997

By Bill Williamson, Doug Richmond, Kerri Kuntz, Gus Gilman, Larry Heywood

This was a description by the poet of what occurred over two centuries earlier to Hannibal’s troops as he passed through the Alps. Interestingly, the pass that many feel is the route that Hannibal chose, Col de la Traversette, is the sight of possibly the earliest avalanche mitigation known. Monastery records describe a tunnel built in 1470, near the top of the pass designed to protect pilgrims from the upper slopes. For the next several centuries, avoidance and reinforced structures were the primary tactics to defend from avalanches

Jan 1, 2009

By B T. Lusk, John J. Silva Castro

The signature hole method uses a convolution operation to predict the waveform of a production blast based on the record of a waveform produced by a single blast hole. Convolution is a mathematical operation on two functions, (generally the product) to produce a third one. Recent research communication and publications highlight a lack of discussion in the literature about the available methodologies to calculate the convolution for blast vibration prediction. The goal of this paper is to discuss and present in detail for students in ground vibrations from blasting, several techniques to calculate the convolution between signals when the signature hole method is used. Convolution is a straightforward operation when signals produced by each hole are assumed the same, however; variations in the signals from each hole in a production blast require a more complex convolution operation. A graphical procedure is shown in this paper to solve a convolution when signals vary hole-to-hole (as expected in a mining production blast). The graphical methodology was tested using a recorded blast event and the results were compared to the regular mathematical procedure (convolution) and the results from a commercial software used in the mining industry. Results show that the graphical procedure is in agreement with the results from the other two.

Jan 1, 2014

By Mathias Jern, Ruilin Yang

A blast vibration model has been developed that simulates effects of almost all blast design parameters on the blast vibration peak particle velocity (PPV) from a production blast with multiple blastholes at a given point of interest in the rock. The velocity of detonation (VoD), initiation points, explosive types (density, VoD, energy), charge decoupling, and decking in each blasthole are simulated along with other blast design parameters. The information from signature hole blast vibration and the blast design are the input to the model. The model can be used to assess blast damage in proximity of blastholes as well as far field vibration PPV.

Jan 1, 2019

By R. Wharton, M. Bagley

The paper reviews the likely introduction of a European directive covering the sale of pyrotechnic articles in member states of the European Union. The background and structure of the directive are described, together with the range of products covered (which includes fireworks, theatrical pyrotechnics, vehicle airbags and seat belt pretensioners, and certain cartridges). Possible timescales and the implications for industry are also discussed.

Jan 1, 2007

By Jean-Sébastien Lambert, Serge Roberge

"At the end of 2014, Holcim Canada (Demix Aggregates Division) considered the possibility of drillingand blasting a big volume of rock in order to expose a high-quality limestone bench in one of their urbanarea quarries in Laval, Quebec (Canada). The project includes many challenges and has thus been qualified as a high-risk operation."

Jan 1, 2016

By Peter N. Calder, John N. Tuomi

The development of a successful control blasting program for an open pit iron mine in hard jointed rock is described. The objectives and mechanics of control blasting are discussed. Design and implementation procedures, which should have wide application, are given. Small diameter angle hole pre-split blasting, buffer blasting with production holes in front of pre-split lines and in front of strongly defined rock structures, and vibration control of production blasts are dealt with.

Jan 1, 1980

By Mats Keisu, Bengt Niklasson

The Sofia project has increased the level of knowledge and technique within tunnelling, drifting and contour blasting.

Jan 1, 1992

By Ginn Huh

The blasting work to construct a subway in Seoul, Korea have often caused increased neighbor’s complaints because of ground vibration. In order to prevent the damage to the structure, it was necessary to predict the level of blasting induced vibration and to determine the maximum charge weight per delay within an allowable vibration level. The effect of blasting pattern, rock strength and different explosives on the blast-induced ground vibration was studied to determine the maximum charge weight per delay within a given vibration level. The blasting vibration was measured from 10 sites along the subway line in Seoul and an empirical particle velocity equation from over 100 test data was obtained, V=K(D/W1’3 )-” , where the values for n and K are estimated to be 1.7 to 1 S and 48 to 138 respectively.

Jan 1, 2000

By S A. Steyn, I P. Douglas

Duvha Opencast is a large South African dragline operation supplying coal to the Duvha Power Station which is operated by Eskom, the state power utility. For Duvha to remain competitive with other collieries, it has proved necessary to continuously examine and investigate methods of reducing costs. With explosives representing a major portion of the total working costs, blasting is an obvious area of investigation.

Jan 1, 1991

By Geraldine Woods

I work for the State of Washington as an Explosives inspector. My paper will describe the mission of the Wa. State Dept. of Labor pertaining to explosives and the regulation of explosives in the State.Blasting safety is high on the public safety list and the regulation of explosive use and storage has been mandated through legislature. The Dept. considers pro-active partnering forexplosive safety preferable to after-the-fact citations for non-compliance.In some cases, the Dept. will issue civil citations with monetary penalties, meant to be a deterrant, of course, to blasters who choose not to comply with the explosive regulations of the State.The Dept. has also revoked and suspended blasting licenses. In some instances, the Dept. has allowed recipients of citations with monetary penalties to reduce the amount paid by attending technical training classes. The idea here, is to reduce the chance of reoccurence of unsafe blasting practices. The State of Washington partners with MSHA in the regulation of explosives use and storage in mines, pits and quarries in the Stateas well as working closely with law enforcement, State and local fire marshals, ATF,and is active in ISEE in part of it’s ongoing effort to promote explosive safety and establish communications in a nonadversarial way with explosives users. My paper will include some statistics on licensing in the State, pounds of explosives used, inspection numbers, numbers and types of complaints with information from the inspections resulting of these complaints. My paper will include examples of storage, both good and bad, examples and pictures of fly rock incidents, accidents, near-miss close calls, break-ins, thefts, and abandoned explosives. This paper may also include a brief summary of my opinion of explosive regulation and my job as a regulator, including examples of high and low points of the job, joys and frustrations.

Jan 1, 2002

By Gordon M. Matheson, Douglas A. Anderson, David K. Miller

"Traditionally, analysis of vibrations from blasting has been focused on peak particle velocity fordetermining the likelihood of both annoyance and damage. The US Bureau of Mines, in RI 8507,indicated the importance of frequency in vibration. Methods of controlling the vibration by reducingthe vibration concentrated in certain frequency bands using delays have been successful over the past decade."

Jan 1, 1997

By Dale S. Preece, Steven Knudsen

A discrete element computer program, DMC (Distinct Motion Code) was developed to simulate blast-induced rock motion. To simplify the complex task of entering material and explosive design parameters as well as bench configuration, a full-featured graphical interface has been developed. DMC is currently executed on both Sun SPARCstation 2 and Sun SPARCstation 10 platforms and routinely used to model bench and crater blasting problems.

Jan 1, 1994

By Greg Rappard, Francois Holowenczak, James Rickard

The King George V (KGV) Shaft forms part of MTR Corporation Limited (MTRCL) Works Contract 703 extension of the underground West Island Line on Hong Kong Island. The Shaft and the associated adit was the sole access to excavate the running tunnels. Originally during the Detailed Design stage, it was concluded that blasting was not feasible at the KGV Shaft due to the close proximity of sensitive receivers in the form of residential buildings, electrical cables and hospitals. As a result, the Contractor planned to excavate the Shaft using mechanical means with a programme time of seven months. The Contractor appointed a Sub-contractor to analyse the feasibility of excavating the Shaft by blasting. The Sub-contractor reviewed the proposal and recommended the use of an innovative blasting technique that had never been previously employed in Hong Kong. The Sub-contractor recommended the Shaft be blasted using DetNet electronic delay detonator technology, manufactured by AEL Mining Services in South Africa, with an initial 1.5m depth of water ballast covering the blast face. The electronic delay detonators provided initiation accuracy to ensure there would be no overlap between sequentially detonating blastholes. The water ballast makes use of the effect of energy lost through the shock front causing the water to break up into droplets creating a spray dome resulting in the attenuation of the energy imparted into the surrounding rock mass. Various tests have demonstrated that both the maximum overpressure and impulse density are significantly reduced when water of a minimum depth is in direct contact with detonating explosives. This innovative blasting technique reduced the excavation programme by three months, saved HK$5 million in direct costs and totally mitigated the impacts on the public and other stakeholders nearby the KGV Shaft. Peak Particle Velocities (vibrations) rarely exceeded 2-3mm/sec (0.08-0.12in/sec) at a distance of 30-40m (98-131ft) from the blast location and air overpressure levels were reduced below the Hong Kong target level of 120dBL. In total, 24 blasts were fired with an average advance of 1.6m (5.25ft) with an average powder factor of 2.03kg/m3 (0.127lb/ft3) to 1.84 kg/m3 (0.114lb/ft3). The initiation pattern had 5ms between sequentially detonating blastholes and 20ms between adjoining rings.

Jan 1, 2013