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By Dave Proudfoot, Mike van Wyk

"There has akvays been plenty of discussion around the ‘accuracy of pyrotechnic detonators withmost recognised manufacturers claiming a variability of arourid 1% or less for their ‘superaccurate’ pyrotechnic based detonators. It is only now being understood that this 1% variabilitycan have serious adverse effects on blast performance. For example a 1% accurate 500millisecond shock tube detonator can fire anywhere between 485ms and 515ms. When wecouple these rather inaccurate ‘accurate’ detonators with short delays on surface, such as a 17millisecond connector, the probability of delay crowding and even out of sequence firing is quitehigh."

Jan 1, 1998

By Don Rapp, Rufus Flinchum

Air blast and flyrock are two of the most critical concerns facing the blaster of today. This paper will provide the blaster with proven procedures for recognizing open face and bench surface problems, explain various surveying methods, and provide the mathematical formulas for calculating and designing proper hole placement and explosive load configuration. A concept called "Pattern Footage" is utilized in conjunction with a USBM study to develop blast designs aimed at minimizing air blast and flyrock. In addition to this main focus, this concept can be used in shot displacement and cast blasting design.

Jan 1, 1993

By Robert B. Hopler

Hercules Incorporated has designed, developed, and begun introducing a new non-electric delay blasting cap system which is radically different from anything presently available. This system, called Hercudet™, utilizes no wires or detonating cord. Instead, each cap has two plastic tubes attached to it. These tubes contain no coating or other materials other than dry nitrogen to extend storage life. In use, after connecting the tubes together with external sleeve connectors, the circuit is checked with a specially designed tester. When the blast area is cleared, the circuit is filled with a gas consisting of an automatically proportioned mixture of fuel and oxidizer gases. When the circuit is fully charged the gas is initiated by special means within the Hercudet™ blaster. The reaction that then travels throughout the circuit has no distruptive effect on the tubing, and virtually no noise is produced.

Jan 1, 1975

By Dale S. Preece, Lee M. Taylor

Computer simulation of the physics involved in conventional rock blasting can be split into two phases; transient stress wave propagation and rock motion. Because the two phases involve totally different mechanisms and time scales, they must be numerically modeled with two different computer programs. The first phase is usually modeled with a finite element or finite difference code which treats the rock as a continuum and simulates the transient stress wave and subsequent fragmentation of the rock. The second phase is usually modeled with a distinct element technique where the rock mass after fragmentation is no longer treated as a continuum but as a finite number of distinct particles that interact with each other through collision mechanics.

Jan 1, 1989

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

By Stephen P. Case, Stephen Castellucci, William Parsons

In this paper, the authors present a step-by-step discussion of dimension stone production at a New England granite quarry. The quarry mines a rare pink granite which is used for facings and panels in the construction of high rise buildings around the world. The discussion includes geological considerations, block layout, drilling, explosives loading, block handling, and mobile equipment utilization.

Jan 1, 1990

By Earl C. Hutchison, John Loviza

At the Metropolitan Nashville International Airport, with its more than 600 scheduled daily flights from American Airlines hub operations, other scheduled airline flights, Tennessee Air National Guard operations, as well as numerous industry air flights, the excavation of 300,000 cubic yards of rock was required without disrupting airport operations for a cut and cover underground tunnel with a 4 lane US Highway and new airplane runway to extend across it's top. In addition to the excavation, the removed rock was to be broken to specification type that was clean and of small size for fill in another area of the airport property. The blasting was limited to two 1/2 hour windows per day and stiff monetary penalties were in place for schedule slippage of each phase of the project.

Jan 1, 1992

By Chantale Doucet, Yves Lizotte, Alan Cameron

A joint Federal Government-Industry research project on the effect of geology on the fragmentation of rock excavated by blasting in underground developments was conducted at the CANMET Experimental Mine, near Val d’Or, Quebec. A total of thirteen (13) blasts were studied from November 1994 to February 1995. The analysis of each blast was divided into three stages: pre-blast characterization, including structural mapping, assessment of Rock Mass Ratings (RMR), Tunneling Quality Indices (Q), blast design documentation; blast characterization comprising blast vibration monitoring and analysis; and post-blast assessment comprising fragmentation assessment by digital photoanalysis, calculation of half cast factors and measurements of bootlegs.

Jan 1, 1996

By S S. Kahlon

India is a large and growth market for explosives and accessories, which has dramatically changed from complete import dependence to self sufficiency, and now has an exportable surplus. The largest single user is coal mining which is continuing to show a healthy growth with opencast mining becoming increasingly dominant. The explosives industry has kept pace with mining and today all the well renowned explosives technologies of the world are available in the country. While slurry explosives are popular in large diameter, NG based explosives continue to be preferrred in small diameter usage. Emulsion explosives have had a good market response. ANFO usage is limited due to local reasons. As the mine size is increasing, the demand for bulk-on-site explosives is growing. Prices of explosives and accessories are cheap compared to international levels. The user industry is mainly Government owned mines whose profitability is not satisfactory. Explosives industry is over licensed in terms of manufacturing capacity, which is likely to put pressure on the viability of some of the explosives manufacturing units. Scope exists for optimization of blasting parameters through the use of computerized blasting models. The explosives industry is faced with new challenges and opportunities.

Jan 1, 1987

By Paul Worsey, Ron Ecklecamp, Scott G. Giltner, Ronnie Inman, Terry Drechsler

A blast monitoring program conducted at Chemical Lime Companys new lime calcining facility near Ste. Genevieve, Missouri is discussed. The purpose was to develop blasting criteria for the construction and operation of the lime plant within the quarry operated by Tower Rock Stone. Further, it was imperative to accommodate production requirements into the blasting criteria. The major concern was the effect of blasting on the curing of green concrete during the construction of the storage silos and kiln stacks. In addition to discussing the susceptibility of curing concrete to blast vibrations, the paper also details how this varies with time.

Jan 1, 1996

By Daniel Haines, Benjamin Konshak, Michelle Crull

American Technologies Incorporated Group (ATI) is the prime contractor with U.S. Army Corps of Engineers, Huntsville Center (CEHNC) in the Honolulu District for the removal of munitions and explosives of concern (MEC) at the Former Waikoloa Maneuver Area. The site is approximately 123,000 acres on the Big Island of Hawaii, which was used as an artillery firing range with live ammunition and other explosives deployed. ATI utilizes state of the art metal detection equipment to find and excavate metallic anomalies that have hazard potential. Both the investigation and disposal procedures present challenges due to residential communities and archeological sites that are located in and around the site. In order to excavate metallic anomalies safely and without adverse impact, ATI utilizes CEHNC-designed, open front barricades constructed of sandwiched sheets of aluminum with a support structure. When munitions or explosives are located, ATI is responsible for safe disposal using shape charge perforators to detonate the item where found. Sandbags are used for mitigating the effects of all detonations.

Jan 1, 2008

By Richard Dooley

This paper is one sided because it presents the problem, but not the solution. The problem of blisters (bubbles) and occasional tears in caisson liners occurred when blasting and we have not found a conclusive cause nor a preventive solution. (For back ground information, consult Techniques of Precision Blasting in the Excavation of Drilled Piers, by George Mosteller at the Sixth Conference on Explosives & Blasting Technique in Tampa, Florida 1980).

Jan 1, 1983

By Ray Heater, Qian Liu, Alan Bauer

The channel effect is a phenomenon that takes place with decoupling explosive charges; an air shock wave propagating ahead of the detonation wave in the annular space around the explosive charge compresses the charge so that the process of detonation is modified and even stopped. For commercial explosives, such as AN/FO slurries and emulsions, the channel effect causes partial detonation under certain conditions. To simulate and evaluate the phenomenon, a hydrodynamic model was developed based on the assumption that the pre-shock wave is produced by Mach reflection at the tube walls. Based on instrumented experimental studies with the above explosives in diameters ranging from 25 to 90 mm in pipe sizes ranging from 35 to 127 mm, it has been possible to demonstrate that a criterion for failure based on a critical impulse concept fits the experimental data well. Critical impulse values for the various explosives tested are presented along with the necessary correlations between charge and borehole diameter required to produce this.

Jan 1, 1988

By Douglas R. Burns

Complying with SARA-Title III and the Emergency Planning and Community Right-To-Know Act as a Non-Manufacturing Facility. As of August 23, 1988 non-manufacturing facilities storing end using chemicals which require MSDS (Materia1 Safety Data Sheets) must fi1e with SERC (State Emergency Response Commission), the LEPC (Loca1 Emergency Planning Commission), and the loca1 Fire Department a list or copies of all MSDS sheets with the Tier I and Tier II forms completed.

Jan 1, 1989

By Brian Stump, Rong-Mao Zhou

A series of single-fired (simultaneously detonated) explosions were conducted in an Arizona copper mine. The explosions spanned yields from 1700 to 13600 lbs (773 to 6169 kg) and were all detonated in an approximate 100 m by 100 m area. In order to quantify the effect of the mine free-face, the individual explosions were also detonated under three different emplacement conditions including at the free-face of the mine under normal burden, twice normal burden and fully contained. The purposes of these experiments were to investigate: (1) Generation of in-mine and regional phases such as Pg, Pn, and Lg from mining explosions; (2) Quantification of the relationship between yield and seismic amplitudes; (3) Quantification of the effect of confinement; and (4) Similarities and differences between single-fired waveforms and those from delay-fired explosions. Instrumentation was deployed at near-source (100-700 m) and in mine (1-5km) distances. Empirical scaling relations for the different shots in this test series were developed in order to quantify the effects of yield and confinement.

Jan 1, 2006

"Recently, an effort was made to calibrate the Riedel-Hiermaier-Thoma (RHT) material model to reproducethe behavior of granite under impact and explosive loading conditions. The study concluded that the materialmodel captured the phenomenon of compressional damage in granite due to such loading conditionsfairly well. The present work uses hydrodynamic modeling with the calibrated RHT model to estimate thefines generated around a blasthole. This can improve the calibration of different size-distribution empiricalmodels and enhance the prediction of fines."

Jan 1, 2012

By Robert A. Cortese, Lon D. Santis

This paper describes a method of measuring continuous detonation rates using standard electronic parts, coaxial cable, and a data recorder such as an oscilloscope. Three six-volt lantern batteries or a DC supply power the electronics that cost less than $100. Included are means of showing low battery power, finding the proper voltage scale on the recorder, and test triggering of the recorder. Modifications of the circuit allow for use in the field to measure charges up to 57 meters and for use in the laboratory to measure short charges. The high resistance (8.709 Ohms/meter) coaxial cable is a mass produced, special order cable available commercially. The driver circuit delivers a constant current to the cable, and as the detonation shorts the cable, a change in circuit voltage occurs. Recording this voltage change over time allows determination of detonation rate resolute to the sampling speed of the recorder. An oscilloscope or personal computer with a data acquisition card can easily record the data for analysis. Detonation rates recorded in the laboratory using the coaxial cable and the Bureau of Mines's traditional probes are presented. The system accurately measured the detonation rates of ANFO confined in steel pipe, detonating cord, and unconfined high explosive.

Jan 1, 1996

By Yonghun Jong, Chungin Lee

The main purpose of this study was to apply the artificial neural network (ANN) models to determine optimal powder factors and predict peak particle velocities, based on a series of observations and input parameters. The used blasthole pattern was V-cut. The locations of blastholes and ignition patterns remained almost constant. The input parameters were 14 geological conditions (i.e., dip, dip direction, spacing, separation, and persistence of 2 discontinuity sets, tunnel orientation, rock strength, RQD, and RMR) and 4 blasting conditions (i.e., distance between blasting points and measuring points, charge weight per delay, drilling length, and blasting efficiency). Data for the ANN application in this study were recently collected in a highway tunnel under construction in Korea. The main rock type in the site was biotitic granite. An optimum ANN model was determined by training models with collected data. The trained model was used to evaluate the prediction capability of the optimum model. It was shown that the ANN model could predict the powder factor and the peak particle velocity depended upon the selected input parameters. Particularly, the ANN model predicted more accurate peak particle velocities than those obtained by the blasting vibration equation. Moreover, the more dominant factors among the input parameters could be determined by analysis of the relative strength effect.

Jan 1, 2002

By Lon Santis

Although unproven, it is suspected that there have been eleven locations since 1988 where explosive generated carbon monoxide (CO) gas moved through the earth and accumulated in nearby underground enclosed spaces. This paper summarizes the incidents, which involved about 30 suspected or medically verified CO poisonings and 1 fatality. Ten incidents occurred in residences and one occurred in a manhole. Although practically nothing is known about the mechanism behind the suspected gas migration, review of the incidents and available information indicates there are certain warning signs and a successful remediation technique available. In each case, overburden heavily confined the explosive in the blasts, preventing release of explosive-generated gases to the atmosphere. All the blasts were in residential areas, and none were excavated immediately. Where the distance from the blast was recorded, 5 of the blasts were within 20 to 50 feet (ft) (6 to 15 meters [m]) of the underground enclosed spaces, 3 were 100 to 150 ft (30 to 46 m) away, and 1 was 400 to 500 ft (120 to 150 m) away. Investigators often identified suspected pathways from the blast site into the underground enclosed spaces. One technique appeared successful at quickly correcting an existing condition. This technique involved applying negative pressure to the earth and removing the CO from the ground surrounding the underground enclosed space.

Jan 1, 2001

Bloomfield Collieries Rix’s Creek Mine is an open cut coal operation located in the Hunter Valley region of Australia. The mine produces approximately 1.1 mt of saleable product per year and routinely employs cast-blasting practices for its unique dragline-truck overburden excavation method.

Jan 1, 2006