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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 Abdulkadir Karadogan, Zikri Keti, Umit Ozer, Mehmet Aksoy, Ulku Kalayci

This paper presents an investigation about how the motions of blast induced vibration waves were affected by the presence of the fault planes. This study was carried out at Espey Open- Pit Boron (Colemanite) Mine in Turkey. Within the scope of the study, ground vibration components were measured for 8 shots using 9 vibration monitors, considering the direction of the fault. Measurement stations were located around the fault line that intersects the open-pit mine in the north-south direction and on different benches along the fault plane. Then, the data of the vibration components obtained from the 77 recorded events were analyzed and the results were presented.

Jan 1, 2012

By Richard J. Mainiero, James Q. Wheeler, Lewis H. Kopera, Yael Miron, Solin S. W Kwak

The research reported here was part of an effort to evaluate the safety of a process to recover TNT from MK-9 depth bombs by the autoclave meltout process. In this process the depth bombs are heated to 121oC so that the TNT will melt and run into a vat. Unfortunately, asphalt lining the inside surface of the bomb also melts and flows out with the TNT. Prior to this study, it was not known what effect the asphalt contamination and the higher than normal process temperatures (121oC) would have on the sensitivity of the TNT.

Jan 1, 1996

By David A. Smith, B L. Jr Lindsey

Arkansas bauxite varies enormously in its consistency and composition which makes blasting a very difficult operation. Blasting rounds have to be designed based on each particular mine's ore characteristics. The variances are so great in some mines that blasting procedures have to be changed almost daily.

Jan 1, 1979

By John Brennan

The Avalauncher has been an integral tool for avalanche mitigation work for close to 50 years. With their ability to place a kilogram of high explosives up to two thousand meters away, they routinely serve as a short range alternative to military artillery. The Avalauncher’s roots can be traced to a pneumatic baseball pitching machine used by Major League Baseball teams in the United States in the late 1950s. Throughout the decades, many modifications have been made to both the launcher and its projectiles. Current technology has allowed the Avalauncher to attain greater accuracies and operational range. In this paper I plan to cover not only the history of the Avalauncher but also explore its potential future.

Jan 1, 2009

By Harry Verakis, Thomas Lobb

This paper is a summary and an update of the underground mine blasting accident investigations and studies previously conducted by the Mine Safety and Health Administration (MSHA) and the former US. Bureau of Mines. Blasting accidents are usually a small percentage of the total number of mining accidents. However, blasting accidents continue to occur and the severity of these accidents is disproportionately high with respect to other types of mining accidents. In 2000, about 5.7 billion pounds of explosives were produced in the USA. The mining industry consumed the greatest portion of explosives manufactured for blasting with about 67 percent used for coal mining. Metal and nonmetal mining operations account for about 23 percent of the use of explosives. The use of permissible explosives in underground coal mines continues to decline (3,373,069 pounds for 2000).

Jan 1, 2002

By Bradley C. Paul

Similar rock formations exhibit great variability in resistance to fragmentation during crater blasting. This observation was made during an attempt to calibrate the Kuz-Ram blast fragmentation model for crater blast geometries used in a modified in situ mining method for copper. The KuzRam equation is used to predict the fragment size distribution from blasting and includes a term called the "rock factor" to account for the fragmentation characteristics of the material. A data base of field scale crater shots in oil shale was available to supplement more limited data on copper ores. First, the blast geometry terms of the Kuz-Ram formula were modified to fit field data with various crater blast geometries. Rock factors were chosen to center the predicted curve on the curve representing observed fragmentation. Next, five possible sources of variability in rock factor were investigated: the grade of the oil shale, the aspect ratio of the charge, the type of explosive, the charge depth, and the rock itself.

Jan 1, 1989

By Andrew Ritter, Victor I. Montenyohl, Stephen R. Winzer

Thirty-seven open pit production blasting operations have been monitored using high-speed cameras running between 500 and 7000 frames per second. Analysis of the resulting films reveals irregularities in timing including sequencing errors and crowding (holes firing less than 8 ms apart), confirming results of laboratory testing of ms delay blasting caps (Winzer, 1978). Where blasting parameters are otherwise constant and within recommended guidelines (stemming, spacing, burden, etc.), timing problems dominate the overall performance of the blasting operation. Model tests in layered Homalite 100, designed to simulate joint or bedding planes in rock, indicate the importance of the stress waves generated by the explosive in developing the crack network which is ultimately responsible for the fragmentation seen in the resulting muckpile. These mechanisms are strongly supported by high-speed film studies at Pinesburg, Maryland. Experiments in controlling relief in deep shots (where depth approaches the lateral extent of the bench blasted) using borehole geometry and hybrid initiation systems (electronic timer and pyrotechnic delays) were carried out. The results suggest that the 1 me/ft. of burden guideline developed by Bergmann et aI., 1974 is too short, and that much longer times are necessary to optimize fragmentation and muck digability. Longer times are found to reduce noise, vibration, and flyrock.

Jan 1, 1979

By Greg Mclellan, Mark Johnson, John Pepper

In this paper, the measured vibrations are plotted in terms of the individual PPV components versus Scaled Distance (SD) on logarithmic scales. The maximum PPV is pIotted on a separate graph and equations are presented to predict the maximum PPV based on sealed distance and prediction level usmg power fits. The prediction levels include a 99.9% curve, which encompasses the data points and provides an envelope formula for determining the maximum PPV at South Florida sites. The dominant frequency distribution is established for the PPV components.

Jan 1, 2001

By Marcia Harris, Richard Mainiero

The New York State Department of Transportation recently commenced highway widening and drainage improvement projects in Clarence and Amherst, NY. Drainage improvements including the installation of storm sewer lines required excavation to a depth of 2.5 m (8.2 ft). In September 2002, NYSDOT stopped further blasting when 800 ppm CO was detected in the basement of a house near the blasting site. At the insistence of NYSDOT, the general contractor developed a new blast plan with the assistance of an environmental consultant. The plan provided for the installation of multi-gas monitors in buildings of special concern and/or with basements and residential type CO monitors in all other buildings within 100m (330 ft) of the blast. The multi-gas monitors would be remotely monitored. The plan provided action levels which would ensure public safety. The blast design was also modified to allow for better venting of CO. Blasts were limited to 20 ft lengths. The overburden was to be removed from the rock and blasting mats put in place to prevent flyrock. Approximately twenty feet of trench adjacent to the blast was left open to allow ground movement and gas release. The use of CO monitors was effective to alert occupants of a building to the presence of CO. The most effective appeared to be the residential type CO alarms with digital readouts. They were simple and easy to use and allowed the public to participate in the process. False alarms were repeatedly received with the more sophisticated instrumentation. Residential type CO monitors are preferable to warn people near blast sites. More sophisticated instrumentation should be avoided unless personnel are experienced in its use. A general overview of the blasting and monitoring is presented and discussed. The use and effectiveness of residential type CO monitors and multi-gas monitors are discussed.

Jan 1, 2004

By Harry Verakis, Thomas Lobb

A great deal of information has been presented and published on the danger from flyrock created from blasting operations. The creation of flyrock is not specific to any one blasting operation. Flyrock is certainly not a stranger to blasting operations conducted in the mining industry and its effects are well known. Flyrock is among the leading causes of mine blasting injuries. Awareness and diligence is the message that must continue to be stressed and followed to reduce the potential for creating flyrock from blasting operations and to reduce the hazard it presents. A recent accident that resulted in a serious injury at a limestone mine in Pennsylvania bears witness to the ever-present danger of flyrock created from blasting operations.

Jan 1, 2007

By M-C. Lee, Shomaker, R. Turcotte, B. Short

This research program was undertaken to better understand the factors causing abnormal NOx fumes generation from blasting operations in surface coal mining. More specifically, unusual quantities of nitrogen dioxide and nitric oxide have been observed at several surface coal mines in the Powder River Basin, Wyoming. All these mining operations have several points in common: (i) Blasting is performed using gravity loaded emulsions or emulsion/ANFO blends (ii) Unusual NOx (Oxides of Nitrogen) emissions are observed mostly when blasting is conducted in the overburden as opposed to the coal seam itself (iii) The overburden consists of very weakly consolidated ground strata, providing relatively weak confinement conditions for the explosives, and (iv) Significant ground water is observed.

Jan 1, 2002

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 Bob de Raadt

After a review of the general principles for blasting stacks, the stagnations of two stack demolitions are investigated. The author concludes and demonstrates that MS-delay blasting can be risky under certain circumstances. How this initiation device can still be applied safely to the demolition of stacks is shown in an account of a blasting operation, in which two 106-m (350 ft) -high concrete stacks were involved. The recent discovery of a possible hazard of MS initiation in this field of blasting is an essential contribution to increased safety in blasting tall structures.

Jan 1, 1982

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 Zhang Qi

For the most part, the flying piece is serious endangerment in the demolition blasting. To prevent the endangerment, a large number of materials are needed as the protection. Therefore, the determination and design way of the flying distance of piece in demolition blasting have been concerned extensively. Previously, the experienced or half experienced formula was adopted to calculate the distance of the flying pieces. The calculating values of the distances of flying pieces are not identical with the practice results. The problems concerning the design way of flying distance of pieces are researched in the paper.

Jan 1, 1994

By Douglas A. Bartley, Davey Bickford, Raphael Trousselle

The long awaited arrival of a high accuracy detonator to reach the explosives end user will provide new opportunities the blasting community to become better equipped and able to improve upon the current approaches and methodologies used in blast design as they apply to the mitigation of adverse effects from blasting. This paper will detail the approach and findings throughout a several month research project to quantify the high accuracy detonator benefits and to mitigate a long standing vibration problem at a hard rock stone quarry in the state of New York. The tests conducted in this study were designed to provide important information as to the relationship between the use of high accuracy detonators and overall blast performance in terms of ground vibration prediction, control and improved rock fragmentation.

Jan 1, 1998

By Joe Dannenberg

A word of preface: The material contained in this talk is not completely original. Many thoughts and actual words come from a fine little book called "1,000 Years of Explosives" by William S. Dutton. The book is now out of print, but if there is enough interest shown by this Society, perhaps we can have it reprinted.

Jan 1, 1980

Several surface coal mining operations in North America are attempting to adapt microprocessor-based monitoring equipment as well as programmable logic controllers onto rotary blasthole drills, towards improving overall drill and blast productivity. These Monitoring While Drilling (MUD) systems permit the recording and processing of important drilling parameters such as rotary speed and torque, instantaneous penetration rate and weight on the bit, and enable the operator ultimately to optimize drill and bit performance. MWD systems on production drills in surface coal mines offer the potential to define mine bench geology in detail and in advance of explosives loading. Recent advance s in explosives and initiation technology will require such a detailed knowledge of ground conditions in order to be fully exploited. Additionally, the logic developed from drill monitoring technology will eventually enable full drill automation through feedback and control, once a more complete understanding of the influences of rock mass characteristics on machine performance is achieved.

Jan 1, 1988

By J R. "Dick" Daniel

One of the more common tasks in blast management is the adjustment of: shot geometry, explosive energy, and shot timing parameters to achieve changes in blast outcomes and costs. Many of these shot parameters, once a delayed blast is initiated, are modified by the development of new free faces which change the original or static input values to dynamic values. These newly generated dynamic values are easily calculated and find use in fine tuning shot adjustments and in rationalizing blast outcomes in a systematic manner.

Jan 1, 1996