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By John L. Floyd

The use of explosive energy to displace overburden or waste material can provide substantial savings to operations which normally rely on mechanical means for material removal. To optimize the available explosive energy, it is important to quantify the rock's response to the type of explosive and explosive accessories used. During a blast, rock breakage and movement occur so rapidly that the naked eye cannot detect the details of the fragmentation process. A relatively high speed motion picture camera (500 frames per second) can provide the extended time base needed to analyze in detail the site-specific rock response to the explosive detonation. The data of importance to blast casting that can be quantified from these films includes initial face movement, trajectory of rock, and differential face velocities of the material shot. In addition, the ground swell velocities, stemming confinement, and stemming ejection velocity can be determined. The performance of explosive products and delay element accuracy can also be ascertained. The use of high speed motion picture photography and analysis can reduce the number of field trials necessary to maximize explosive performance and increase the benefit provided by blast casting, and in turn, lower production costs. This paper will discuss the methods used for data accumulation and analysis. In addition, three field studies conducted at three separate mining operations will be presented.

Jan 1, 1988

By D. C. Valdemeri, Oppermann J. P. Z., R. G. Schaarschmidt, C. S. Mendonca

This case study was conducted in an aggregate company, located at Estância Velha town, RS, Brazil. The study was based on the results of vibration monitoring mainly in terms of PPV (peak particle velocity) and frequency. Changes in the blasting design were performed to adjust the limits determined by the Brazilian standard NBR 9653:2005. Understanding the seismic wave attenuation for the site, changes in the blasting design were tested to fit the limits, such as reduction of maximum charge per delay, initiation orientation and sequencing and finally the replacement of accessories like "shock tube" by electronic initiation system. The results are shown below.

Jan 1, 2015

By Sheila Luchansky, F M. Babcock, Daniel M. Sanders

A cooperative effort between a blasting vibration consultant, a blasting contractor, and personnel from the City of Las Vegas has dramatically reduced complaints from residential areas near developmental blasting projects. The principal methods used involved the preparation of an informative video recording which presents various aspects of the blasting operations, the design of a distinctive flyer which is attached to residential doors, and pre-blast meetings for information dissemination.

Jan 1, 1993

By Cathy McGinley, John Mullay, Clark Stancavage

The use of crater studies to evaluate explosive performance is a well-established practice in the Blasting Industry. Normally, this work utilizes larger charge sizes (>75mm) in order to minimize the influence of geological factors adjacent to the borehole. This can impose unwanted restrictions in the experimental factors accessible to investigation. Thus, for example, systematic studies of non-ideal performance in a somewhat practical setting is rendered quite difficult.

Jan 1, 1995

By Zhang Shixun, Wang Xuguang, Zhong Yinting

The Mongol-Russian Joint Mining and Processing Cu-Mo Corporation Erdenet signed a contract with BGRIMM for building a plant to produce 10,000 t/y multitype emulsion explosives by using BGRIMM emulsion explosives manufacturing technology. In order to ensure the realization this contract, we have done a series of studies on the design of technological process and the selection, layout of the production equipment, and made a success.

Jan 1, 1997

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 Gordon M. Matheson, David K. Miller

Sinkhole development in karst terrains is a serious problem and risk to facilities built in these areas. The potential for sinkholes are a function of many things including the chemistry of the underlying rock, the location of water conductive fractures and fissures in the rock, the natural fluctuation of the ground water table, vibrations from various sources and surface regrading activities. When sinkhole open near quarry operations the occurrence of these features is occasionally attributed to vibrations from quarry blasting. The purpose of this paper is to review the evidence regarding the development of sinkholes as a result of quarry blasting. In general, it has been found that sinkholes result from collapse or piping of overburden soils into cavities or caverns developed within underlying carbonate rocks that have been in existence for many thousands of years. The overburden soils in karst areas are typically clayey and as a result are not subject to densification or liquefaction as a result of vibrations. The primary cause of an increased rate of sinkhole development can be attributed to changes in the ground water table or local surface water drainage. These changes may be caused by seasonal fluctuations, ground water level lowering in drought periods, dewatering of excavations or quarries, or local changes in surface drainage resulting from grading activities.

Jan 1, 1998

By John Wright

As part of the redevelopment of the Royal Brisbane Hospital complex in Australia, a number of antiquated buildings were to be demolished and replaced by newer, modem facilities. Aside from the decommissioning of the hospital buildings, the project called for the removal of approximateIy 24,000 bank cubic metres (bcm) of varying quality rock material. Given the sensitivity of the project, in particular the close proximity of the required excavation to the existing hospital structures (-3 metres at the closest point), and the requirement that these were to remain lily operational during the construction phase, it was initially proposed to use hydraulic rock hammers as the primary means of excavation. Poor production rates and unexpected dif3icuIt rock conditions led to a revision of the excavation methods and a feasibility study on drill and blast practices was undertaken. Subsequent to an initial series of trial blasts to illustrate that vibration and flyrock could be adequately controlled, drill and blast methods were used in conjunction with mechanical methods of rock breakage. This paper reviews the drU and blast processes and the practices which were necessary to comply with the multiple constraints imposed on the project. The project has highlighted that modified drill and blast practices remain a cost-effective method of excavation, even in sensitive areas which are commonly deemed inappropriate for such methods.

Jan 1, 2000

By P. R. Mohanty, Kaushik Dey

Blast-induced tunnel overbreak prediction in the past has been based on peak particle velocity measured far from the blast site with necessary extrapolation. This has often resulted in suggesting higher damage threshold levels of Acceleration/PPV for overbreak prediction (Bogdanhoff, 1995, Holmberg and Persson, 1997, Murthy and Dey, 2002). These, site-specific far-field blast vibration studies, have also revealed that predicted PPV levels for overbreak could lie in the range of 700-5000 mm/s, an extremely wide range to generalize. Experimental blasts were conducted, in an underground metal mine located in eastern India, with an objective to study the level of acceleration /peak particle velocity generated in tunnel blasting. Accelerometers and tri-axial geophones with measuring ranges upto 500 g, 254 mm/s respectively, were mounted on the tunnel floor close to the blast face, with sensor distances varying from 15.25m to 36.10m. Due to straight faces the measuring distance could not be reduced further anticipating, in particular, cable damage. The equipment used was of M/s Instantel Inc., Canada. The blast pattern used was burn cut with large dia relief holes providing the required free face. The blast hole depth was 1.8m. Tunnel overbreak was measured using a telescopic offset rod fabricated at Indian School of Mines, Dhanbad, India.

Jan 1, 2004

By Robert Hopler

INTRODUCTION NOT so very many years ago the farm was about the last place where one would expect to find up-to-date mechanical appliances. Steam, explosives, electricity—the factors which have made the world in general, and America in particular, what it is today— were indispensable for the railroad and the steamboat, the factory and the mine, but the farmer’s work was generally run on a comparatively small scale, and was mostly done by the muscles of men or draft animals. Today, however, the farmer as well as the manufacturer, the contractor and the miner, fully appreciate the value of labor-saving devices. Every up-to date farm, large or small, has modem machinery that tends to reduce the cost of production or to improve farm products.

Jan 1, 2011

By S. Mandal, R. Singh

The demolition of structures with explosive though most rapid, safe and efficient requires planned blast design parameters with respect to geometric and strength properties of the structure to be demolished. The paper, here deals with successtil demolition of three old bridge piers by different blast designs. These piers were 11 m tall and very close to the existing bridge, The plan distance of the old piers from the existing bridge varied between 43 m and 14,25 m. The paper also deals with the mathematical concepts for the causes of such action of demolition/dismantling of structures.

Jan 1, 2001

By F. Malek

An extensive blast monitoring program has been carried out to study explosive performance and the effectiveness of blast designs in production blasts in a deep underground mine. Comprehensive monitoring of blasting vibrations through multi-station high-capacity high-frequency accelerometers, and borehole deformation history have been the main tools of such analysis. The mining activity involves relatively unstressed stopes as well as highly stressed stopes. More than 30 production blasts have been monitored, and the respective vibrations from close-range as well as distant seismic stations have been analyzed, and the vibration parameters (amplitude and frequency) have been correlated with explosive charge weight in the holes. It is found that the correlation between blasting rounds and the corresponding vibration amplitudes often have poor correlation for a very significant portion of the blasts. These point to either explosive charge malfunction in those specific blast holes, or inadequate blast design, or the effect of high in-situ stresses, or any combination thereof. This paper analyzes these variables and their effect on the overall blasting operation at the mine.

Jan 1, 2013

By Richard J. Mainiero, Eric S. Weiss

This project investigates the behavior of blast waves from the detonation of high explosives in an underground mine. A series of explosive tests was conducted in the underground and surface facilities at the Bureau of Mines' Lake Lynn Laboratory to evaluate the potentially dangerous effects of blast waves produced by open shooting, blown out holes, or accidental detonations of explosives. Shots of C4 and TNT were fired at the dead end of a 6 ft high by 20ft wide entry, at the intersection of two entries, and on the surface. C4 and TNT were chosen for this research because they exhibit very consistent performance. Behavior of the blast wave was evaluated through recording of the pressure as a function of distance from the explosive detonation.

Jan 1, 1995

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 R R. Singh, U K. Dey, S K. Roy

"Commercial explosives being a heterogeneous mixture of many chemical compounds in prefixed proportion, their velocity of detonation (VOD) may vary from batch to batch, due to variations in the proportion of the chemical composition and process parameters even within their tolerance limits. Inherent limitations of measuring methods and human variations during measurement also add to the variation in VOD values determined practically. Therefore, it is customary to define a range of VOD values rather than a fixed value of VOD for a particular explosive.Variations in VOD values of four commercial permitted explosives in India were evaluated under open unconfined condition using Dautriche method and a resistance wire method based continuous VOD meter. Comparative evaluation of VOD values of selected explosives were aimed to check the relative effectiveness of continuous VOD measurement of small diameter cartridged permitted explosives using cheaper co-axial wire instead of recommended costly VOD rods along with the continuous VOD meter. Results of evaluation revealed that continuous VOD of commercial small diameter cartridged explosives could be determined using cheaper co-axial resistance cable with comparatively better accuracy than the most commonly used Dautriche method."

Jan 1, 2007

By Ivan Kovac, Pero Marjanovic, Branko Bozic

"The paper deals with results of geophysical survey of the rock masses, and the blasting parameterswhich have effect on the fragmentation in quarries . A relationship between the burden, which is the distance between the charged borehole and the free rock surface, and the velocity of longitudinal waves in the rock mass is established based on measured values for different quarries. It is shown that the drilling geometry can also be detemrined from this relationship."

Jan 1, 1999

By John P. Ashby

Production blasting is a process of destruction of rock masses in order that ore may be extracted. Many open pit operations are faced with the apparently conflicting requirements of providing large quantities of fragmented rock for the processing plant and of minimizing the amount of damage inflicted upon the surrounding pit slopes. A reasonable compromise between these two conflicting demands may often be found by means of simple engineering of production blasts.

Jan 1, 1980

By Walter Jr Duke

The security of explosive materials is a vital concern to every mine, quarry and contractor engaged in blasting. Proper construction of magazines and sufficient locking mechanisms are the fundamental means of maintaining secure storage. The object of this paper is to review the proper methods of construction of storage facilities for explosives as defined by the Alcohol, Tobacco, and Firearms regulations. Subpart K subsection 55.208 and the Institute of Makers of Explosives recommendations.

Jan 1, 1991

By Paul Downing

A major component of an effective blasting company safety program is the self-audit. A self-audit can help reveal hazardous conditions that should be corrected and training needs that should be addressed before accidents occur, insurance claims are filed, and/or fines are levied. Such audits, when they lead to appropriate corrective action, can provide significant economic benefits for employers by reducing the costs associated with insurance claims, accidents, and injuries.

Jan 1, 2001

By Gerald R. Coonan

Laboratory research is being conducted to substantiate suggested levels for voluntary standards on human response to transient vibration. The application of those findings to actual field conditions, however, will be limited because they will not include social and psychological factors existent in the real world. It is necessary, therefore, to examine available empirical information on complaints in an attempt to define the influence social and psychological factors might have on the laboratory results.

Jan 1, 1982