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By Joe Dannenberg

One must be cautious in talking about blasting safety, because the very act of making a blast involves the creation of an infernal machine. You are setting up for the instant release of tremendous energy. Inherently this is a hazardous act. It has always been hazardous. It will stay hazardous.

Jan 1, 1975

By J W. Edl, F C. Wu

In instrumented model rock blasting experiments in granite blocks, best fragmentation results were obtained when delays between holes were 1 to 2 milliseconds per ft. of burden and when a rectangular shothole pattern was used with spacings larger than the burden. Effective fragmentation in multiple hole blasts seemed to depend primarily on the full development of the crack network around each hole before the charge in the next hole was detonated. The test results showed that simultaneous or almost simultaneous initiation of shotholes in bench blasting resulted in poor fragmentation.

Jan 1, 1975

By Deane Boddorff

A 440 Volt AC power line is a typical power source for energizing electric blasting cap circuits in driving hard rock tunnels. A common misconception exists that the caps actually see 440 Volts. This paper describes an analysis of the entire blasting circuit determining the current flowing and the voltage drops through each component. If, from such an analysis, one determines that the current to the caps is too low or too high, the components that require changing are easily recognized.

Jan 1, 1975

By Richard L. Ash

A question that frequently arises during litigation concerned with accidents or alleged damages involving blasting is "were the explosives used according to the best known standards"" The question is not confined to only law suits, however, but also everytime poor blasting results occur. Unfortunately, general guidelines that can be used to define what may be considered as proper practice have not been established by any responsible body upon which to base a reliable Judgment; more often than not decisions are made primarily according to personal opinion.

Jan 1, 1975

By C F. Argo

In the past several years the "Kelly Bar", an innovative device, which incorporates borehole d-rifling and explosives loading into a single detail, has come under scrutiny and criticism. The practical aspects of the Kelly Bar procedure is not questioned, and the system has been highly successful in expediting the loading of explosives in difficult and unstable formations. There have been a number of accidents indirectly associated with Kelly Bar loading and the point in question has become one of safety rather than mechanical feasibility.

Jan 1, 1975

By Henry P. Van Ormer

This paper discusses some basic fundamentals in compressed air system design and layouts that should always be considered in planning or evaluating a compressed air distribution system in Construction and Mining. Often times, mining operations use central air or "power house" type systems that more closely resemble a typical industrial or plant compressed air distribution system. This paper does not attempt to cover this type of system.

Jan 1, 1975

By Edward Jr Walter

This paper discusses the problems that arise in the process of developing adequate explosives noise legislation. Case histories are used to illustrate how and where these problems arise and the course of action followed in overcoming them. It is imperative that those concerned keep informed as to possible legislation and be prepared to present solid facts that will insure fair and reasonable controls.

Jan 1, 1975

Almost one half of Canada's total land surface is underlain by permafrost. This term describes the thermal condition of earth materials when their temperature remains below 0°C continuously for a number of years. The drilling and blasting of frozen materials requires more energy than the blasting of same in its unfrozen state. The cost of comminution could double in permafrost even with adequate organization, drilling equipment and proper explosives.

Jan 1, 1975

By Lawrence W. Hallanger

Anaheim Bay, located at Seal Beach, California, is the site of the Huntington Harbor development of waterfront homes and marine facilities. The main entrance to Anaheim Bay is a relatively narrow channel connecting the bay with the Pacific Ocean which runs under California State Highway One. During the development of Huntington Harbor the old highway bridge was replaced with a new, higher bridge to allow for boat passage through the channel. At that time only the main span decking of the old bridge was removed, leaving the support pillars and the approach ramps in place (see Figure 1). The narrowness of this channel, plus the increasing boat traffic created a situation in which public demand for the removal of the old bridge became significant. Because the bridge was located within the boundaries of the Seal Beach Naval Weapons Station (see Figure 2) the Navy became involved in the bridge removal. Eventually the task was assigned to the Naval Amphibious Construction Battalion One and work began in early 1974.

Jan 1, 1975

By F Hunyadi

The seismic effects resulting from blasting are still a problem today although a great deal of research has been conducted in this field. A great amount of data defining the seismic effects can be collected with the proper instrumentation, however because of the difference in building materials, construction methods and foundations the characteristics of the seismic wave can not be directly correlated to the building response and possible damage.

Jan 1, 1975

By Duane Skidmore, Calvin Konya

The supply crunch and cost rise for ammonium nitrate (AN) over the past year have been influenced by a number of factors. These include a general inflationary tendency, particularly great cost rises in fuel, and by a market condition in which demand for ammonium nitrate is great and supply is limited. Demand is largely confined to agricultural and explosives uses with explosives subdivided into mining, construction, and quarrying. The projections show that demand may be expected to increase markedly for the indefinite future in the agricultural and mining sectors of the ammonium nitrate market while fluctuating with indicators of economic activity for the construction and the quarrying sectors. Supply is projected to increase with plants being designed and built due to high need levels and commensurately high profit potential but not enough are planned to provide an equilibrium market. Constraints upon supply increases to match demand increases include shortages in the raw material, natural gas, high cost of investment capital, high equipment costs and long construction delays. The result should be, even under optimistic conditions, considerable shortage and resultant pressure for higher prices through 1979 for ammonium nitrate. The best hope for relief in the intervening years appears to be conservation. In blasting operations, the earliest and best proven route to conservation seems to be improved utilization available from application of highest available technology and most efficient current blasting practice.

Jan 1, 1975

By Charles W. Trettel

Confined explosives upon detonation produce a chemical reaction generating expanding gases that result in fragmentation of matrix a chemical to mechanical transition. A 100% energy conversion during transition is difficult, if not impossible, to achieve. There are numerous variables that affect energy transition. Although fragmentation is the most often used criteria to determine shot efficiency, the escaping energy profile provides additional data as to the efficiency of a blast. Escaping energy can also have deleterious effects in the form of ground motion.

Jan 1, 1975

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 Donald J. Moore

It has become more important today than ever before to reduce costs and improve equipment utilization. One area where such improvement can he achieved is in the use of explosives. Effective blast design for efficient use of explosives as well as optimum fragmentation can achieve this. Towards this end we must have available to us a practical design method in which experience and observation can be translated to engineering concepts. We must he able to communicate the design data to field blasting personnel as well as management in an understandable way.

Jan 1, 1975

By Carlyle F. Bunn

The source of the standards adopted by the Occupational Safety and Health Administration are outlined. Preplanning to eliminate violation of the standards and improve overall job efficiency are discussed.

Jan 1, 1975

By Herschel Sanson

Success of underground blasting operations depends upon a number of interrelated factors. These include conditions at the place, blasting methods, face preparation, type of cap, powder selection, transportation and storage. In addition, much of the work is closely regulated by state and federal regulations.

Jan 1, 1975

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 Robert F. Dexter

This paper discusses the Federal requirements of this regulation for the importation, manufacture, distribution and storage of explosive materials. The interstate or foreign commerce in explosive materials, licensing of manufacturers, importers and dealers, issuance of permits, the conduct of business by licensees and operations of permit tees and the storage of explosive materials.

Jan 1, 1975

By Christodoulos Xiouris, Ali Reza, James Karnesky

A rocket parachute signal flare is often used to signal a maritime emergency. In the general operation of these devices, a solid rocket motor propels a metal body to an altitude of approximately 1000 ft(305m).At the end of the rocket motor, a propelling charge drives a signal flare and parachute out of the metal body and ignites the flare, which then burns for approximately 40 seconds as it falls to earth. In this paper, we describe an engineering investigation of an accidental ignition of a rocket parachute signal flare, which caused injury to the user. The components of the flare involved in the accident were inspected via x-ray and microscopic imaging techniques, and compared with those of unfired flares recovered from the same vessel. Chemical analysis of residue on recovered components from the accident flare was also performed. These comparisons were used to determine the likelihood that the actuation mechanism had been deliberately manipulated. In the subject model of the flare, ignition of the rocket motor is accomplished through a percussion cap which is struck by a firing pin. Prior to activation, the firing pin holds down a pre-compressed spring. We present a comparison of the ignition system of the incident flare with those of other rocket parachute flares, which do not incorporate any stored mechanical energy.

By Catherine Johnson, Barbara Rutter, Phillip Mulligan

Shock tubes, shock tunnels, and blast tubes have been widely used by explosive researchers and shock wave investigators to understand the characteristics of shock waves. Rectangular, cylindrical, and conical are the three simple geometries commonly used in shock tube and shock tunnel testing. These geometries result in shock waves that resemble the Friedlander curve’s simple exponential decay. However, geometries that are more complex have not been studied. This research investigates how changes in shock tunnel geometry affect the pressure versus time waveform. The Large Arena Test Simulator (LATS), which is composed of four different rectangular sections connected by three expansion sections, was used to determine how the changes in geometry affect the shock wave profile. Shock wave profiles were measured inside and outside the LATS to investigate the geometry’s effect. A representative shock wave profile from each geometry and open-air explosive testing were compared visually showing the geometries effect on the shock wave profile. The LATS produced a waveform with four pressure peaks behind the initial shock front, which were found to be associated with the four rectangular sections. The resulting pressure trace was compared to pressure traces from simulated urban bombings. The number of turns in an urban environment equated to a new peak, which is caused by additional expansion sections of the shock tunnel. From this observation, complex geometry shock tunnels can be purpose built to simulate an explosion in an urban setting. The use of shock tunnels with complex geometry in simulating urban bombings can allow for numerous representations and a better understanding of profiles produced during an urban bombing or similar scenario.