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By Dale Preece, Stephen Chung

The DMC-BLAST (Distinct Motion Code) has been developed for modeling bench blasting to one or two free faces such as choked blasting in surface gold operation and cast blasting in coal mining, respectively. This computer code has been used to assist the analysis of rock mass displacement after a blast was initiated in an orderly delay sequence. Applications of this feature can be found in the studies of dilution control in surface mining of gold as well as coal involving complex rock structures. Recently, DMC-BLAST has been modified to include a designated delay firing order coupled with variable rock strengths in the blasted media. This newly added feature allows the investigation of the effects of delay firing order on rock displacement in blasting a complex interbedded ore-waste structure. Examples of blasting a steeply dipping coal seams and bedded rock structure, especially in coal mining operations will be addressed and the comparison of efficiency in blasting in an up-dip as opposed to blasting in a down-dip direction will be discussed. Also covered in the paper is a new application of DMC-Blast to simulate a stope blasting underground. Simulations of blasting in a few selected types of timing/structure combinations will be presented in this paper.

Jan 1, 2000

By Lewis L. Oriard

Both theory and experience tell us that spatially distributed energy sources generate a more complex family of seismic waves than do point sources. The resulting effects in the near field (for close-in blasting) are significantly different than those from point sources although, at great distances from the source, the seismic waves take on many of the characteristics of point sources and can often be treated as such.

Jan 1, 1992

By Kevin Phelps, Jason Baird, Philip Mulligan, Dominique Nolan

Determining the transitions from run-up to optimal cut length and optimal cut length to run down, without bias, from the penetration of a linear shaped charge (LSC) is difficult. The stresses applied to the targets during explosive testing can distort the targets in such a manner that determining the true distance of cut, penetration, or fracture can be demanding. Through the course of this research, it was observed that the researchers made many of the errors involved in the collection of data. Among these errors researchers found problems in: determining and fitting the sample to a single plane from which to read measurements, determining where along the path of cut the three phases of penetration transition, and the precision of measurement based on handheld tools and the human eye. This study looks at three methods of recording the data of a series of linear shaped charge tests. The tests resulted in samples which are not ideal for measuring with common laboratory devices like measuring tapes, calipers, or rulers. The first method utilized these common laboratory devices and the difficulties the authors experienced are described in this paper. The second and third methods involve digital photography, image manipulation, and the use of AutoCAD. Methods two and three are then compared to the simple observational method and discussion is made in regards to the precision and accuracy of each method.

Jan 1, 2013

By Marco Antonio Falquete

Conventional detonators and blasting caps make use, as igniters, of flame-shock-, andfriction-sensitive primary explosives, such as lead azide, lead styphnate, mercury fulminate, etc, most of them severe toxic and environmental contaminants. Sensitivity of primary explosives is one of the main causes of injuries and fatalities in explosives industry and in field applications. Intense research for a reliable, safe, and environmental-friendly non-primary-explosives detonator was conducted by the industry in the last years. A new detonator is presented, containing no primary explosive, employing only environmental-friendly substances while keeping reliability of performance. A series of performance tests is executed in prototypes of different output energies, including initiation by flame, shock tube, thermo tube (IBQ’s proprietary spark-generating tube, presented at 2005 ISEE Conference), energy transfer reliability, and extreme environmental conditions (according to MIL-STD 331B, test C1 standards). Results are compared, when pertinent, with standard blasting caps of different energy outputs, and with standard primary explosives.

Jan 1, 2007

By James W. Reil, Douglas A. Anderson

Common wisdom has it that a blast which breaks rock efficiently should-generate less ground vibration. In practice, however, this idea has not been-rigorously tested. In a previous paper presented at an SEE meeting[1] we described a method for-controlling vibration using delays. The method is very effective in controlling-annoying low-frequency ground vibration. We noted that observed ground-vibration differs in some respects from that predicted by adding single-charge-waveforms.

Jan 1, 1988

By T J. Wilton, K A. Broadhurst

The United Kingdom, although a relatively small island, has a wealth of mineral deposits, coal, granite, limestone, gypsum, lead, florspar, etc. Coal is a major source of energy with 71 opencast coal sites, 52 using explosives. Many of these sites are in rural areas, the average area worked being 250 acres. The smallest is 35 acres, the largest 2,000 acres, but only 600 acres can be operated at any one time.

Jan 1, 1981

By W. Reisz

The fear of heights is a natural defense against performing a dangerous and unnatural act such as standing on the edge of a hundred foot wall. Yet through familiarity, a casual attitude often exists. Those of us, who work near highwalls on a daily basis, may become overly comfortable in our surroundings, losing sight of the disaster which may often rest a single misstep away. And this is where the hidden dangers lie.

Jan 1, 2009

By Ann Barron

Even though you think your company’s safety program is the best it can be, equipment, processes, supplies, surroundings and people do not always behave or react as expected. Consequently, needless accidents occur each year at quarries, construction sites, surface mines, and other locations where explosives are used. While blasting accidents account for only a small portion of the total accidents reported, the severity rate for blasting accidents is higher than for any other accident category.

Jan 1, 2007

By R Yang, D B. Kay

"Blast vibration control is of vital importance for tunnel blasting in urban environments. A vibration model with multiple seed waveforms (MSW) as input for a point of interest was developed in recent years by one of its authors. The MSW blast vibration model has been applied successfully in open cut and quarry blasting situations. From the literature, it appears that there may not be any seed wave-based vibration modelling work for tunnel blasting.A project was conducted to test the MSW model for tunnel blast vibration. A series of tunnel blast rounds were fired and tri-axial vibration waveforms from the blasts were recorded with several seismographs at distances ranging from 10 to 100 metres from the blasts. Seed waveforms were collected and the charge weight scaling law for the signature hole PPV were established.The MSW model is applied to tunnel blasting and specific issues associated with tunnel blast vibration addressed, such as variable effects of confinement and screening to vibration during a blast round. The capability of the model in terms of the PPV and frequency prediction is demonstrated in the paper. The paper demonstrates that the MSW blast vibration model is a useful tool for managing tunnel blast vibration with the potential to optimise round by round design in terms of managing the vibration below the limit while maximising tunnel advance rate."

Jan 1, 2011

By Brian Stump, Chris Hayward

Blasting operations at one copper mine are studied in detail to examine the relation between blast design parameters and near-shot, in-mine, and regional seismic and acoustic observations. Five observational experiments, namely collection of blast design data, near source recordings, GPS synchronized video, near mine recordings and distant regional observations were performed during one week in August. A variety of seismic and infrasound instruments were installed near the shot, on the perimeter of the open pit mine, and at several locations up to 500 km distant. Time tagged video recordings were taken of several shots. Three shots were used in the preliminary analysis, a 350,000 lb pattern with long delays, a 60,000 lb pattern with short delays, and a 256,000 lb pattern with short delays. Maximum peak-to-peak amplitudes of the seismic signals in the mine are not a simple function of the total size of the shot, but are related to the pattern timing. Peak pressures have a less clear relation to peak pressure but match the relative amplitudes of spectra modeled from the pattern design. The predicted spectrum based upon a simple impulse model fits the observed spectrum for ground acceleration measured near the pattern and explains why in this case a pattern of 60,000 lb results in the same seismic disturbance as the 350,000 lb pattern.

Jan 1, 2002

By Raimo Vuolio

"Over the past 30 years, the Nordic countries have developed similar practices for estimating damage caused by rock blasting vibrations. However, over the last few years the risk of damage has sometimes been estimated by using international values, which have created unnecessary costs, since they are too conservative. This paper gives a proposal for Finnish blast vibration standards and a calculation model for the extent of the zones for building inspection, risk analysis, and vibration measurements. The international conclusion is that particle velocity is the best descriptor for limiting damage potential for structures. Over 900 000 vibration data recordings from 52971 blasts were collected for this paper during 1970-1989. They show that the most practical description is the vertical component of the peak particle velocity. As rock is a nonhomogeneous medium, it is hard to predict the need and scope of risk analyses, building inspection, and vibration measurements. As a large number of blasts were monitored for the recording of the peak particle velocity in several locations in Finland, and the data combined, it is possible to establish safe scaled distances for the calculation of the need and scope of risk analyses, building inspections, and vibration measurements."

Jan 1, 1991

By Qingshou Chen, Gongbo Li, Hengqian Ran

A method for safe fracture of rock, concrete and other brittle solid material using dynamic water pressure by explosion is provided. The propagation of the pressure is studied with Allievi water hammer theory. Wave equation and velocity formulas of the pressure propagation are shown. The dynamic water pressure is tested in the lab. The propagation of the pressure is simulated by MMIC-2D. The results of fracturing rock in the lab and on a quarry are presented.

Jan 1, 2000

By C A. "Hawk" Hanger

"The paper that will be presented is an in-depth study of sequential blasting using standardnon-electric shock tube down hole timing along with surface M.S. connector timing.Included also will be a discussion on the advantages in fragmentation, digability, oredilution' and ground vibration versus the common practice of row by row blasting. Alongwith the written presentation, several visual illustrations will be included. The visuals willrefine the actual direction and predicted movement of the shot involved."

Jan 1, 1993

By Tom C. Palangio

Commercially available online particle size analyzers (OPSA) are in their third decade of development (Palangio, T.C., 1985), (Franklin, J. A., Maerz, N.H., 1987), (Maerz, N.H., Franklin, J.A., and Coursen, D.L., 1987). The installed base of operating analyzer numbers is in the hundreds. This paper takes a look at five critically important relationships that users have discovered through the use of OPSA systems. The two key attributes of these systems are: 1) consistency and, 2) historical context compared with traditional practices.

Jan 1, 2016

By Thomas E. Lobb, Harry C. Verakis

Significant progress has been made in the reduction of serious injuries and fatalities resulting from mine blasting operations. Despite the progress, injuries and fatalities continue to occur. A leading cause of injuries and fatalities from blasting continues to be inadequate blast area security. Even though significant improvements in technology have been made, insuring adequate blast area security remains a challenge and requires constant vigilance. The advances in technology have created safer blasting products and have improved productivity and economics by enabling large, more efficient and effective blasts. However, as blasts grow larger in size, the complexity of adequately securing the blast area increases even more. Periodically the basic fundamentals involved in blasting safety should be reviewed, particularly for securing a blast site regardless of the size of the planned blast. Factors such as flyrock and toxic fumes must be taken into account to insure the safety of persons and property from the results of a blast. This paper examines the factors related to injuries due to inadequate blasting shelters and blast area security, and identifies mitigation techniques. The key concepts are: (a) accurate determination of the bounds of the blast area, (b) clearing employees from the blast area, (c) effective access control, (d) use of adequate blasting shelters, (e) efficient communications, and (f) training. Fundamentals are reviewed with an emphasis on analyzing task elements and identifying root causes for selected blasting accidents. Mitigating techniques are presented along with discussions and examples.

Jan 1, 2005

By H P. Rossmanith

This contribution addresses the advanced blasting technology which is based on wave propagation theory and fracture mechanics. The new concept of sonicity and the principle of maximizing sonicity in blasting as well as the energy or work of a blast operation will be introduced. It is shown that - in contrast to common belief – it is not the velocity of detonation which controls the blast but the relationship between velocity of detonation and the wave speeds, in other words, the Mach numbers of the blast operation. Based on numerous practical blasts in Germany, the authors show that, when using wave dynamic concepts, there is a linear relationship between peak particle velocity and the work of a blast operation and this linear relationship is controlled by the sonicity of the blast. Extensions to layered and faulted rock masses are presented. It will become clear that a second change of paradigm is enforced, the first one being the implementation of short time delaying. Again, the acquisition of knowledge in wave progation theory and fracture mechanics becomes mandatory in advanced blasting technology, where the art of blasting is now fully transformed into a science of blasting with little room for methods of trial and error.

Jan 1, 2010

By Dale S. Preece

A Discrete element computer program named DMC (Distinct Motion Code) has been developed for modeling rock blasting. This program employs explicit time integration and uses spherical or cylindrical elements which are represented as circles in 2-D. DMC calculations have been compared with measurements on bench blasts in the field with relatively good comparison. Structural geology and joint sets have a significant impact on any blast and DMC has not, until now, included these effects. This paper discusses a recently added DMC capability for treating joints and bedding planes in bench blast simulations.

Jan 1, 1995

By Joshua Hoffman, Catherine Johnson, Braden Lusk

Blasting conducted in surface coal mining operations in the Appalachian region consumes a significant amount of blasting agents. Emission of oxides of nitrogen (NOx) from these operations potentially represents an environmental challenge. This paper presents work conducted to quantify NOx output from the detonation of blasting agents common to surface blasting operations in surface coal mines. Annual ANFO and emulsion consumption data was collected from an operational surface coal mine located in West Virginia. It is known that many factors contribute to the types of gaseous byproducts released from the detonation of explosives. These factors include but are not limited to: fuel to oxygenator ratio, degree of confinement, and contamination. While, past research has been conducted to study the relationships these factors play on the release of NOx, these findings do not agree with one another. The annual explosive consumption values from the West Virginian mine were applied to NOx emission conversion factors in published literature. This lead to a range of NOx emissions from 95 to 914 tons in a year. Given the wide range of NOx production the utility of this information is suspect. The EPA recognizes a standard factor of 17 lbs (NOx)/ton (ANFO) however this factor is based on chemical composition and does not address contamination, confinement, or AN to FO ratio. This factor when applied to the West Virginia Mine's explosive consumption produced a value of 215 tons of NOx. There is a lack of information on NOx emission from emulsion type explosives. The work presented in this paper can be used by blasting professionals to quantify NOx emissions and guide future work for producing better predictor factors.

Jan 1, 2014

By P Cotton, N Cox

The Brisbane City Council has implemented a program of continual improvement at its Mount Coot-tha Quarry in the heart of Brisbane, Australia. The program has been underway for the past 6 years, and has resulted in very significant improvements in terms of both the cost effectiveness of its operation, and in terms of its environmental impact on nearby residents. The work has included a focus, amongst other things, on blasting efficiency, and has challenged conventional thinking in terms of the size of blasts fired, the frequency of firing, the diameter of blastholes, and the use of bulk emulsion or slurry explosives.

Jan 1, 1995

By Dale S. Preece

A carefully designed and controlled in-place destruction experiment was performed on a concrete bunker buried in 4.27 m (14 ft.) of soil. The objective was to determine if the explosive charges would collapse the structure in-place without requiring mechanical excavation. Collapse of the buried structure was fi rst attempted by drilling holes in the soil and placing four 13.38 Kg (29.5 lb) Comp B explosive charges at a depth of 2.13 m (6.7 ft.). The confi guration of the charges when detonated was 2.13 m (6.7 ft.) off the top of the concrete roof and 3.66 m (12 ft.) apart in a square pattern. Detonation of these charges created a crater ~4.88 m (16 ft.) in diameter and 2.13 m (6.7 ft.) deep, leaving ~2.13 m (6.7 ft.) of soil covering. Very limited spalling occurred on the ceiling of the concrete structure as a result of detonating these four charges. The second attempt to collapse the structure consisted of placing another single 13.38 Kg (29.5 lb) charge, identical to the fi rst four, near the geometrical center of the bunker roof. This charge was detonated in the soil cover 100 to 200 mm (4 to 8 in.) above the reinforced concrete roof, collapsing it. Due to the collapsed roof and remaining soil cover, the structure had been collapsed in place, requiring no further demolition. A computer simulation of the above explosive destruction scenario was completed using the computer hydrocode AUTODYN with a granular material model to treat the soil and the RHT brittle material model to represent the concrete. AUTODYN accurately recreated the scenario including the slightly damaged response of the concrete structure to the initial four charges and the collapse of the structure resulting from the second single charge close to the roof.

Jan 1, 2007