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By Mauro Fornaro, Marilena Cardu, Renato Mancini

Detonating cord cutting is widespread in dimension stone extraction, especially in the case of hard, abrasive stones as granites, an important resource for Italian industry. General data on this production sector are briefly discussed and analyzed in the first part of the paper. The theoretical basis of operation are summarized, and compared to data obtained from selected commercial cases, in the second part.

Jan 1, 1994

By Michael S. Wieland, Thomas C. Ruhe

Delay blasting in underground coal results in shock waves traveling through the coal that can damage delay charges remaining in the blast pattern. Undetonated explosives which are dynamically desensitized or react sympathetically from shock wave impact ruin blast results. Such malfunctions, sometimes manifest as misfires, more frequently are covert weak detonations, and result in poor coal breakage and fumes with above normal toxicity. To reduce these mining hazards and resolve charge performance problems, the Bureau of Mines has developed and tested forty prototype rugged explosives in the laboratory. Rugged explosives work properly under difficult circumstances because they not only retain their shock initiation sensitivity but also are resistant to shock damage. This research investigation resulted in one candidate emulsion explosive, formulation #37, which passed all the permissibility tests required by MSHA approval regulations. However, approval was not granted because it reached shelf-life (would not shoot properly) seven months into testing. For research purposes, the remaining tests were conducted with a second batch of formulation #37. This paper discusses the prototype rugged explosive composition and permissibility test results. Where possible, for reference purposes, comparisons are made to a commercial product that has been approved. Further research work is required to overcome the noted deficiency of short shelf-life.

Jan 1, 1992

By Conny Postupack, Jim Petrunyak, John Loope

The authors discuss the concepts, engineering considerations, and cost relationships involved in the use of drilling and blasting to accomplish backfilling and reclamation with minimum use of mechanical equipment. The four methods of reclamation now in use are reviewed, and their advantages and disadvantages are noted. Guidelines for selecting a particular method are offered in terms of applicability under varying geologic, economic, and technological conditions.

Jan 1, 1987

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 Zoltan Susanszky

This paper discusses problems encountered when blasting under rivers for pipeline crossings. Many pipelines have recently been laid under the Danube River. Great care had to be taken to determine limits of detonation impulses from blasting operations in order that no damage would occur to structures at the water's edge, boats, and swimmers. Equations were derived from the results of this study which enable prediction of impulse levels.

Jan 1, 1977

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 David R. Ziegler

Blasting complaints are as unpredictable as human nature. Being prepared to speak to the complainant, and having a good idea of what you should say, or what NOT to say, may affect the evolution, and eventual resolution of the complaint. The person taking that first phone call will probably not be responsible for resolving the complaint. However, the person in charge should respond to the complainant ASAP, the same day, if possible.

Jan 1, 1998

By J R. Phin

The properties of all available modern blasting initiation techniques are reviewed. Primadets are nonelectric initiators, the nonelectric features of the system eliminates concern of premature initiation from static or stray currents. The loading techniques are simple and a minimum of training is required. There is no limitation in the number of necessary sequences in which the Primadet need be connected for initiation. This flexibility improves vibration control,and often reduces costs due to increased fragmentation.

Jan 1, 1975

By R DeLon Hunsaker

In the past, quarrying and other small operations have not been able to take advantage of the lower cost, convenience and better performance of bulk slurries. However, with the introduction of repumpable emulsion slurries and their ability to be stored in containers as blasting agents, bulk slurries are now available for small operations with small diameter boreholes and are producing excellent results. This same concept is being used successfully in larger underground operations.

Jan 1, 1984

By Shulin Nie

The dead-pressing phenomenon in emulsion explosives is wellknown. Research work on this subject has been carried out at the Swedish Detonic Research Foundation for the last few years. Several experiments with emulsion explosives under dynamic pressure condition have been carried out both in iron pipes and in blast holes in rock. The main object was to study the critical amplitude and duration of the pressure causing the explosive to be dead-pressed.

Jan 1, 1993

By David W. Zeeb

The use of an ordinary VHS video camera and a four-head player can be an effective tool to analyze surface blasting. The necessary equipment can be purchased for under $1,300 and will allow frame by frame or slow motion viewing of a blast in 33.33 millisecond increments. Rock breakage, movement, and timing can be studied in high quality slow motion. These studies can result in improved blasts by showing things that the eye can miss in real time.

Jan 1, 1992

Coal strip mine operators in Western Canada often mine steeply-dipping multiple coal seams in mountainous terrain. The ability to fragment the rock waste layers above and below these seams with minimum disruption of the seams in large blasts normally involves decked charges in large rotary boreholes. Mining these seams may take two or more separate blasts to break the waste wedges above and below the coal, but these wedges can be blasted in a single shot for better mining efficiency.

Jan 1, 1985

By E Emery Jr Gray

The City of Richmond, in an effort to improve sewage treatment facilities, designed an invert syphon to cross the James River at Fulton Bottom. The design criteria called for installation of two 36-inch pipe' lines at an elevation of -35 with the mean water level being at elevation 00. This paper discusses the actual method of construction used to blast the river bottom. Choice of excavation equipment, nature of the river, as well as the geological structure, were taken into consideration.

Jan 1, 1979

By Calvin L. Cumerlato, David E. Siskind

The Bureau of Mines has monitored structural responses to airblast overpressure produced by munitions disposal at the McAlester Army Ammunition Plant. The Purpose of this study was to determine if the blasting caused vibrations, airblasts or structural responses that could possibly be responsible for cracking or other damage observed in nearby residences. Monitoring took place during a 3-month period at 10 selected residences surrounding the plant. By the end of the monitoring period, nearly 2300 blast-related events had been recorded.

Jan 1, 1994

By Jerome S. Brower

Quadrex-L is a two component liquid explosive which was developed by J. S. Brower & Associates, Inc. to facilitate handling and shipping, and use in unique applications, while emphasizing safety. It may be advantageously used for all explosive applications. Quadrex-L can be introduced into a preinstalled container configuration and may be easily drained or flushed from these containers when necessary to do so. This characteristic can be effectively utilized to reduce the hazard period during assembly or disassembly operations.

Jan 1, 1975

By Janos Foldesi, Calvin J. Konya

The determination of the number of primers necessary to efficiently initiate an explosive column charge is essential to good blasting. If the number of primer is insufficient, the total energy stored in the main charge will not be released. On the other hand, the use of too many primers will be counterproductive and raise the blasting cost. Tests were conducted by the authors to determine the correct priming procedure for a basalt quarry. This paper describes the results of those tests.

Jan 1, 1976

By Douglas Anderson

In the early 1980s, a method for controlling blast vibrations other than by modifying the Scaled Distance came into use. Research studies had indicated that blast vibration could be simulated by detonating a signature hole with the vibration monitored at critical locations, and then using a computer to superpose the waveforms with varying delays. By choosing delay times that create destructive interference at frequencies that are favored by the local geology, the “ringing” vibration that excites structural elements in houses and annoys neighbors could be reduced.

Jan 1, 2008

By Theodore C. Hile, Floyd P. Henry, Ken Gragg

"Conventional explosive-storage methods usually rely on combinations of earth and concrete barriers, along with sufficient distance between limited explosive loads, to avoid accidental conflagration. However, under many circumstances, Air National Guard (ANG) facilities co-located with civilian airfields have trouble meeting necessary Quantity-Distance (Q-D) requirements for Explosive Hazard Class/Division 1.1 and 1.4 materials. Because of the danger posed by explosives stored in earthcovered magazines (ECMs) too close to civilian activities, ANG units often find itdifftcult to maintain adequate stores of ordnance needed to meet unit mission goals."

Jan 1, 1999

By Richard J. Mainiero, T S. Bajpayee

The U.S. Bureau of Mines (Bureau) has conducted research to evaluate the firing accuracy of electric delay detonators used in surface blasting operations. Over four billion pounds of explosives and blasting agents are used every year in surface blasting in coal, metal and non-metal mines. In a typical large-scale surface blast, several thousand pounds of explosives are fired in a timed sequence using delay detonators. The delayed firing of explosive charges allows time for the fragmented rock to move out before the next charge is fired.

Jan 1, 1990