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By O E. Jr Crenwelge

Recently promulgated regulations governing blast induced ground vibrations in the mining industry contain a frequency criterion as one option for verifying compliance. This criterion is based upon an oversimplified method which assigns the entire peak particle velocity amplitude to one frequency. Depending upon the nature of the vibration time history, it is possible that this frequency may not even be one of the predominant frequencies of the signal. In addition, the criterion does not specifically define the data analysis approach to be used by the industry for obtaining either the amplitudes or the frequencies of the vibration components. And because personnel in this industry generally have little understanding of vibration phenomena, a number of different approaches are currently being used for satisfying the criterion. This paper presents a method for obtaining both the Fourier amplitude-frequency spectrum and the integrated predominant amplitude-frequency components for the vibration record. The method is both physically and mathematically correct and is in common use in a number of other industries. Therefore, it should be of help to regulators, blasters, and consultants charged with developing, enforcing, or implementing ground vibration criteria.

Jan 1, 1988

By Lon Santis, David Leidel, John Tatom, Meredith Hardwick

This paper describes the development and methodology of the Institute of Makers of Explosives’ Safety Analysis for Risk (IMESAFR), a risk analysis software program for commercial explosives operations. IME is a nonprofit safety and security association devoted to the safe and secure manufacture, transportation, storage, and use or disposal of commercial explosives in the US and Canada since 1913. The software methodology’s basis is the U.S. Department of Defense Risk Based Explosives Safety Criteria Team’s Safety Assessment for Explosives Risk (SAFER) software. A diverse group of industry and government experts contributed to modifications to SAFER that reflect commercial operations. IMESAFR is intended to supplement the American Table of Distances (ATD) and offer standardized methods of managing risk from a wide variety of commercial explosives operations where the ATD does not apply. The modifications made to SAFER primarily involved the addition of commercial activities and potential explosives sites (PES). A review of commercial explosives accidents and operations over the last 20 years served as the basis for establishing probability of event values. An industry survey of commercial PES types in the U.S. and Canada was conducted to identify and address critical differences in commercial structures as compared to the military structures in SAFER. The paper concludes with discussion of the potential uses for quantitative risk analysis (QRA) and a description of other explosion effects software

Jan 1, 2007

By Italo Onederra, Jason Furtney, Ewan Sellers

The Hybrid Stress Blasting Model (HSBM) is a high level blast modelling research tool which provides results that can still be used implicitly for practical blast design. The code is being developed through an international collaborative research project funded by a consortium of companies which is comprised of explosive, equipment suppliers and major mining houses. A key component of the HSBM is the numerical code and user interface designated as Blo-Up 2.5. To date validation work has focussed on breakage, fragmentation and damage outcomes in controlled laboratory experiments and using large concrete cubes

Jan 1, 2012

By Ken Tunnel

In the spring of 2005, the Lake Superior Chapter of the ISEE invited me to speak about raw materials used for blasting, anhydrous ammonia and the effect of this important feedstock on the cost of ammonium nitrate.The invitation was extended because our company is involved in trading ammonia and the production of ammonium nitrate. In a response to a request to update that presentation, it struck me how events such as hurricanes Katrina and Rita can change the landscape of our businesses.

Jan 1, 2007

By Patrick D. McLaughlin, C Fordham

"The project outlined in the accompanying paper was to densify beach sands on the pond side ofa tailings dyke to the strength required for future dyke construction, This was to be achievedthrough the detonation of relatively small explosive charges in the sand to cause settlement intoa denser state."

Jan 1, 1992

By Mark S. Stagg, Rolfe E. Otterness, Farrokh Djahanguiri

The U.S. Bureau of Mines (USBM) evaluated empirical equations that predict fragmentation from underground stope rounds. Controlled blasting is necessary for creating leaching stopes that maximize the recovery and minimize backbreak of the perimeter wall. This paper presents the fragmentation results from one of the three drop-raise blasts used to develop a reduced-scale cylindrical stope, 1.8 m in diameter and 6 m in height. The stope is located in the Colorado School of Mines Experimental Mine (Edgar Mine) in Idaho Springs, Colorado. This stope is part of a USBM research effort to determine the feasibility of incorporating in situ leaching of rubblized stopes into active underground metal and nonmetal mines.

Jan 1, 1994

By G E. Frantii

In the exploitation of low grade mineral deposits, blasting engineers are vitally concerned with maximizing the efficiency of explosive fracturing of rock while simultaneously limiting deleterious environmental affects to acceptable levels. Efficiency can be inferred from radiating seismic waves. Likewise, seismic waves carry direct information on damage potential. The usual approach to this problem is to measure the maximum signal level close to a blast, where it is difficult to instrument and where the signal complexity is intensified by mixtures of wave types and by local heterogeneities. Near-field sites are usually more easily monitored and more readily interpreted. Therefore, a study is being conducted to determine if variations in multi-hole, delayed blasts produce measurable changes in the spectra of seismic waves recorded in the near-field and if these spectra can be correlated with close-in strong motions and affects. To date, power spectra for the well-developed phase Lg and its early coda have been computed and are found to vary measurably when nominal changes occur in blast conditions. Up to a distance of about 50 km the spectra of Lg and its coda appear to be dominated by body wave characteristics (thus source-controlled), whereas beyond 50 km path affects seem to dominate. Additional data must be collected to fully explore the consistency of near-field Lg observations and to verify their usefulness as diagnostics of the engineering affects of blasting.

Jan 1, 1977

By Andy Hudson, Stuart Brashear, David Lilly

Because of greatly increased timing accuracy, electronic detonator systems are a well-known and widely accepted major tool to control and reduce ground vibration. At a Southeastern quarry the authors found that the use of electronic detonators improved the reliability of the well known cubed root scaled distance equation for determining air blast. In addition, the authors noticed significant correlations between selected major peak particle velocity frequencies and air blast magnitudes. The major peak particle velocity frequency alone is a close approximation to air blast magnitudes. This relationship is not as significant or not always evident when standard pyrotechnic initiation systems are used.

Jan 1, 2009

By K Ramachandra Rao

Joints, fractures and other structural defects bring anisotropic character Into a rock mass. Conventional methods of blast design In a rock mass consisting phyllites, mica schist etc., which are characterised by the presence of closely spaced, nearly vertical planar Joints, result In formation of large slabs which cannot be handled by the excavation and loading equipment without resorting to secondary blasting. Frequent secondary blasting Is not only expensive but also, Is a source of environmental hazard. Interruption of production cycles frequently, leads to uneconomical mining. This problem could be minimised by designing blasts which produce forces whose components along and across the joints/fracture planes Is lust sufficient to break the rock mass In both directions. Rock mass strength can be assessed from field and Laboratory tests. Projecting structural features with respect to bench orientation on a stereoplot helps In assessing magnitude and direction of force vectors required to fragment the rock mass to the desired size range.

Jan 1, 1995

By Karl E. Burger

Recently an experiment was completed at the Golden Sunlight Mine, a property owned by Placer Dome Inc. of Vancouver, British Columbia, to measure the Body Waves entering their highwall created by blasting. The purpose of the study was to assess the damaging effects of blasting on the highwall, in order to further slope stability. Stress and Strain experienced in the earth that is created as a result of blasting can be determined by knowing several important pieces of information. These include the compressional and shear wave particle velocities initiated by blasting, the Body Wave travel velocities in both the shear and longitudinal direction, and the densities of the rock in question. A series of equations based on wave theory can then be used to determine the stress and strain affecting the highwalls. The Blasting Engineer can then use this information to design blasts that create peak particle velocities less than levels that maintain the integrity of the highwalls. This paper first discusses the experiment used to measure the Body Wave velocities. It then traces through the subsequent calculations necessary to generate the information needed by the Blasting Engineers, the Mining Engineers, the Geological Engineers, and the Geophysicists to design blasts and develop open pit plans to alleviate unstable highwall conditions.

Jan 1, 1989

By A Gene Riggs

The Cerrejon Coal Project in Colombia, South America is one of the largest coal mines in the world. The mine is located in northeastern Colombia on the La Guajira penninsula. The area is in a remote valley 132 miles east of the city of Barranquilla.

Jan 1, 1984

By I. Petropouleas, J. Croll, R. Bassett

A programme of tests on controlled internal explosions to a class of circular reinforced concrete columns, has allowed the relationships between the blast energy and the extent of local damage to be understood. These tests have also demonstrated the important additional effects on the damage levels of preexisting axial loads.

Jan 1, 2006

By M E. Hanson, K Chong, R H. Jacobson, S C. Way

To create conditions for economic rates of mineral recovery in a deep, hard rock mass, enhancement of naturally occurring permeability is necessary, and may be achieved through explosives detonated in boreholes. Previous theories of explosively created permeability are reviewed and found to relate permeability solely to the degree of fracturing, neglecting porosity. A theory is presented that includes both fracture density and porosity, and its results are applied, together with a knowledge of explosive behavior, to derive design parameters for in-situ mining.

Jan 1, 1983

By Robert C. Brown

During a research period lasting over three years, a vast number of seismograms were collected and analyzed. From this data, other than obtaining a host of new information pertaining to the effects of surface mine blast on underground mines, it was found that by mounting seismograph velocity transducers at the center of crosscuts in underground mines, seismograms can be obtained which give fairly accurate information about the maximum levels of vibration, and the associated Of stresses and strains, misfiring of blast holes, delay accuracy and delay overlap. The technique of analysis is a simple one; it involves matching of the frequency of wave or wave groups with the shot card information such as rows of holes, number of holes and the cumulative milliseconds of delays used in the blast holes. Any discrepancy that might exist between the frequency of waves and the expected cumulative millisecond delay for a given row or hole eventually will show up as a mismatch in the analysis. This simple technique enables the seismographer to be involved not only in the monitoring of blast peak vibration, but also in making recommendations as to the choice of millisecond delays, reducing the possibility of delay overlaps and reducing the hazards of blast hole cutoffs.

Jan 1, 1980

By Dennis J. Viscusi, James H. III Rowland, Lon D. Santis, Mark H. Weslowski

This paper describes the procedure for analysis of toxic fumes from the detonation of high explosives using the Large Chamber at the U.S. Bureau of Mines (USBM), Pittsburgh Research Center (PRC). This test is specified in 30 Code of Federal Regulations (CFR) Part 15.20 (g) as a requirement for the Mine Safety and Health Administration's (MSHA) approval of an explosive as permissible for use in underground coal mines. The Large Chamber replaced the Bichel gauge and CrawshawJones (C-J) apparatus in the 1989 revision of these regulations. To determine the safety of an explosive in terms of toxic gas production, the Large Chamber Test attempts to simulate mine conditions and miners' exposure to toxic gases from explosives.

Jan 1, 1995

By P Bellairs

The Hamersley Province is located 1OOOkm to the North of Perth .the Capital City of Western Australia and is of major economic significance due to the mining of extensive deposits of Haematitic Iron Ore for both domestic and export use. A small but significant proportion of the waste associated with these deposits presents problems due to its ability to spontaneously combust and react with explosives resulting in premature detonations.

Jan 1, 1996

By Cathy Aimone-Martin

The City of Henderson, Nevada is experiencing extraordinary population growth. Some residential development requires blasting to be conducted at close proximities to high-value houses. Blastingrelated concerns voiced by the community residents include dust, noise, fears of damage to residences, and claims of insufficient controls exercised by the blasters. Residents perceive geological conditions are adverse to the protection of structures at the current vibration regulatory limit of 0.5 in/s. Airblast limits are 120 dB. Vibrations felt within structures leave home owners with the perception that damage is taking place. New cracks appearing in homes at distances far from the blasting are being blamed on blasting.

Jan 1, 2007

By Frank Sames

Blast vibration and airblast overpressure signals are generally rated and compared only by their maximum amplitude and the principal frequency associated with the peak pulse. The scaled distance concept is often used to predict peak amplitudes and can be applied for blasts in the same area of a mine to evaluate the statistical properties of a set of readings.

Jan 1, 1997

By Calvin J. Konya

Precision Blasting has designed easy to use, yet, highly powerful databases for storage and retrieval of blasting data. Three different Databases are available for blasting data management. The Vibration Data Management is a complete vibration record keeping system. The Blasting Data Management will record the information from the blasting report as well as the vibration data. The Explosives Inventory Control makes the control of explosives and initiators quick and easy.

Jan 1, 1991

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