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By Roger E. Scholl

Data on off-site low-rise building damage from underground nuclear testing at the Nevada Test Site (NTS) of the United States Atomic Energy Commission (AEC) [The AEC has been called the United States Energy Research ant Development Administration (ERDA) since 1975, but because the data presented here were gathered between 1966 and 1970, the AEC rather than ERDA is referred to in this paper.] are available for seven large tests in the period from 1966 to 1970. The data, while sparse, provide an adequate sample for the investigation of motion-damage relationships. Damage in the study is statistically described in terms of the incidence of damage complaints, the incidence of buildings damaged, and damage cost. Using 5%damped response spectrum acceleration amplitude to characterize ground motion, the plotted data fit reasonably well with previous motion-damage relationships established from extensive data available from the 1969 RULISON underground nuclear explosion (UNE) experiment conducted in western Colorado.

Jan 1, 1976

By Catherine Johnson, Kelly Williams

The ability to measure the overpressure of a shock wave is necessary for explosives research such as shockwave focusing and field testing of blast-resistant designs for buildings and vehicles. To record the peak overpressure of the nearly instantaneous pressure rise at the shock front, pressure transducers with a fast response rate and streamline pencil design are needed. Time spent setting up sensors coupled with the expense of high-frequency data acquisition systems, and the inconvenience of low impedance cables can make the process challenging. Additionally, only small inaccuracies in sensor position can drastically change the measurement recorded. Advances in high-speed video imaging make it possible to see the refraction of light due to the high-density gradient at the shock front without the need for parabolic mirrors or additional light sources necessary for Schlieren or shadowgraph imaging. The average shock front velocity between two points can be calculated by dividing the change in position by the elapsed time between the images. Using the Rankine-Hugoniot relationship demonstrated by Swisdak the peak overpressure of the shock wave can be calculated from its velocity eliminating the interference of the gage and mount. This paper investigates the accuracy of this method by setting dual transducer pencil probesat0and180 degrees perpendicular to the central axis of a285-gram(0.63-pound)cylindrical charge to record pressure versus time for comparison to the high-speed video. The axis of the camera lens is aligned with the central axis of the charge with both pencil probes in view. The pencil probes have two pressuretransducersset100millimeters (3.9 inches)apart to measure the time of arrival and are used to validate the velocities calculated from the high-speed images. This method can be used to evaluate the shock wave propagation from more complex prismatic charges with different cross-sectional shapes where precise placement of cumbersome pencil transducers in the near field is almost impossible.

By D Linn Coursen

In the proposed method, the charges are elongated and arranged in one or more arrays. The orientation of each charge in an array, its velocity of propagation of explosion, and the velocity of propagation of vibration in the formation are such that, at an outlying location where vibration is to be reduced, the onset of vibration from explosion of the first negligibly small increment of each charge arrives a finite time before that from explosion of the last negligibly small increment of that charge. The charges of each array are fired in accurately-timed sequence, with the times between initiations chosen so that, at the outlying location, the onset of vibration from explosion of the last small increment of each charge, except the last charge, arrives a negligibly small increment of time before the onset of vibration from explosion of the first negligibly small increment of the succeeding charge. With such timing, vibration may be reduced at the widest range of locations by tilting the boreholes so that the terminal end of each charge is directly above or below the terminal end of the succeeding charge.

Jan 1, 1995

By James Rowland, Marcia Harris, Richard Mainiero

This paper reviews the potential hazards posed by the toxic fumes produced by detonating explosives in surface mining and construction operations. Blasting operations produce both toxic and nontoxic gaseous products; the toxic being mainly carbon monoxide (CO) and the oxides of nitrogen (NO x ). The quantity of toxic gases produced by an explosive is affected by formulation, confinement, age of the explosive, and contamination of the explosive with water or drill cuttings, among others. Techniques to protect workers and the public from the potential hazards of explosive-related toxic fumes are discussed.

Jan 1, 2007

By D Maxwell Ellett

This report presents an evaluation of knowledge concerning a process used in predicting ground motion resulting from large scale conventional explosive detonations, The shots were set off in Arizona in connection with copper ore recovery activities.

Jan 1, 1976

By Rob Famlield, Gavin Yuill, William Birch

The Blasting Research Group at the University of Leeds, in the United Kingdom, continues to be highly active in the area of the environmental impact of blasting. In recent years a major part of this research has been concerned with the use of linear superposition. This technique relies upon the assumption that all the holes in a blast produce identical vibration signals. Previous work at the University has shown that this assumption is not sufficiently robust to be generally applicable. This is due to a number of factors of which the key variable appears to be dynamic confinement

Jan 1, 2002

By Michael F. Barber

"Highway slopes are intended to remain stable over a long period of time. Unexpected slope failures can be costly in terms of human life and property damage or loss. Cleanup of failures can prove to beextremely expensive."

Jan 1, 1999

By William McFerren, Pragasen Moodley

In contrast to global trends, African, especially South African, surface mining operations have shown a significant rate of adoption of Electronic Detonators (ED’s) over the last few years. Proven benefits of converting to ED’s from pyrotechnic initiation systems have aided this market conversion. These benefits are experienced throughout the mining operation. Benchmarking exercises, prior to the introduction of ED’s, form part of the conversion process and allow for quantifying improvements. Extensive work has been done on quantifying the benefits of converting to ED’s and have shown that results can be reproducible. Improvements have been experienced in many applications and include environmental impact control, improved mining efficiencies, increased cast benefit and improved size distribution. These step changes in blasting results, in conjunction with the adoption of ED technology have aided the rapid conversion of the African surface market.

Jan 1, 2004

By Roberto Golchi

This article describes the method used to quantify the Environmental Impact for the mining, by drilling and blasting, of a borrow pit for a gravity-dam. The affected environment was broken down into a number of components, such as public health and safety, social relationship, air and water quality, flora and fauna. The effect of the various impacting factors from the mining activities, both directly and indirectly, was then calculated for each environmental component. To do this, each impacting factor was first given a magnitude, a number based solely on the range of scenarios possible for the impacting factor. A matrix of weighting factors was then derived to systematically quantify, and normalise, the effects of each impacting factor on each environmental component. The overall impact upon each individual environmental component was then calculated by summing the weighted magnitudes for all the impacting factors.

Jan 1, 2003

By Dale S. Preece, J Paul Tidman, Stephen H. Chung

"A discrete element computer program named DMC-BLAST (Distinct Motion code) has been under. development since 1987 for modeling rock blasting (Preece & Taylor, 1989). This program employsexplicit time integration and uses spherical or cylindrical elements that are represented as circles in2-D. DMC-BLAST calculations compare favorably with data from actual bench blasts (Preece et al,1993)."

Jan 1, 1997

By W. Reisz

The fear of heights is a natural defense against performing a dangerous and unnatural act such as standing on the edge of a hundred foot wall. Yet through familiarity, a casual attitude often exists. Those of us, who work near highwalls on a daily basis, may become overly comfortable in our surroundings, losing sight of the disaster which may often rest a single misstep away. And this is where the hidden dangers lie.

Jan 1, 2009

By Stanton Johnson

Africa has a long history of mining and has been one’of the world’s greatest sources of gold and other mineral resources since the days of the Egyptian pharaohs. Mining in Africa has been dominated by South Africa since World War II. However, in the past 10 to 15 years, other African countries are beginning to slowly catch up with South Africa. Ghana, formerly called the “Gold Coast” is located on the West Coast of Africa. Ghana has been involved in mining activities for well over 100 years. Most of the mining activities centered on the mining of gold and were to a large extent limited to underground mining methods. With a more liberal economic policy regarding the exploration and exploitation of Ghana’s mineral resources, mining activities are beginning to evolve to a much larger scale. Drilling and blasting which is an important aspect of this evolution is also changing due to the involvement of foreign-based mining and explosives companies.

Jan 1, 1998

By Jack Eloranta

Transmission of sound through the atmosphere is affected by local conditions. Anecdotal accounts of the sound of cannon fire traveling great distances go back to the Civil War. The Royal Society published a paper near the turn of the century concerning the reports from the cannons fired in London at the funeral of Queen Victoria. Early computers were used by the U.S. Army at Aberdeen in Maryland in the 1950’s to model airblast problems during munitions demolition. Today’s blaster has to have access to weather information beyond a simple local forecast. Surface winds, winds aloft and temperature profiles have a dominant role in neighbors reaction to blasting. Many ground vibration complaints are really airblast complaints. Blasters who maintain ground velocities under . 1 inches/ second are often perplexed by complaints from distant neighbors, even when local monitoring shows airblast to be under 110 dB. This paper will help the blaster identify warning signs of high airblast conditions.

Jan 1, 2000

By Jason Rock, Rob Thompson, Lee Julian

Reactive ground is ground that undergoes a spontaneous exothermic reaction after it comes into contact with nitrates. This is commonly caused by inert rock hosting sulphide minerals, such as pyrites that act as the reagent. The presence and subsequent rate of reaction with nitrate based bulk explosives can be difficult to predict. Once identified, only explosives that are tested and proven to be compatible with the reactive ground may only be used. These typically take the form of inhibited ammonium nitrate emulsion blended with a limited volume of ANFO or porous prilled ammonium nitrate (PPAN) to ensure that all AN prills in the blend are wholly encapsulated and thus protected from the reactive ground. The requirement for high emulsion content bulk products limits the suite of products available for use to high energy, and high expense products. Further, if chemically sensitised products are used, charged holes must be left unstemmed to allow for gassing to occur, adding delay and exposing the blast crew to an unconfined charge in reactive ground. A range of inhibited products has been developed that are solid sensitised and can be bulked to as low as 0.9 g/cc (56.2 lb/ft3). The use of a solid sensitiser enables stemming to occur immediately after each hole is charged, confining any unplanned detonation more safely within the rock mass. The effective and precise manufacture of bulked inhibited products required a new and innovative Mobile Processing Unit (MPU) design. This MPU required the ability to blend two solid raw materials (AN prill & sensitiser) along with two liquid ingredients (AN emulsion and process fuel). This MPU has been designed, manufactured and has used successfully to manufacture low density inhibited explosives. This paper presents an innovative shift in inhibited bulk products with specific reference to their manufacture and application.

By Derek T. Novotny

Blasting cap precision is of major importance to advanced blast design. New technologies have introduced the use of microchips within detonator casings in the hope that the electronic control of the timing element will increase the accuracy of the cap and therefore improve the results of perimeter control blasting applications. The electronic detonators have proven to be accurate in timing tests done to date. They boast cap scatter results to microsecond accuracy, but the question is, does this degree of accuracy actually prove to be beneficial during practical use in the industry, or are conventional technologies applicable.

Jan 1, 1998

By Joshua Hoffman, Rob Farnfield, Catherine Johnson, Braden Lusk, Morgan Lane

IMESAFR (IME Safety Analysis for Risk) is a quantitative risk assessment software tool developed by the Institute of Makers of Explosives (IME) and A-P-T Research, Inc. It is used for managing risk in the commercial explosives industry, the newest version of the software was completed in 2012. This paper discusses the use of this software package in conjunction with data collected for a television series on the reenactment of the ‘London Blitz’, a 57-day bombing of the City of London in 1940. In this reenactment, purpose built structures using period design and materials were constructed at a test facility in the North of England. Five devices ranging in size from 20 kg (44 lb) to 1100 kg (2400 lb) were detonated at varying distances from the structures; each blast was monitored by EPC-UK and the resulting structural damage was analyzed. Data recorded from the blasts included high-speed videos, photographs before and after each event and air overpressure readings. The same data was inputted into the IMESAFR software package to assess the risk imposed on the residents of London during this time. The appropriateness of this tool for evaluating structures built using historical practices is discussed. Data from the full scale tests is compared to effects predicted by IMESAFR. Further analysis of the risk recommendations produced by IMESAFR is compared to the actual damage assessed during the large scale tests.

Jan 1, 2014

By Oliver Finn

Gold dredging has made such rapid strides of late and there is such a widespread interest in this branch of mining that I venture to contribute a detailed account of the way in which a Keystone driller was used by me in California to loosen, by blasting, a very tight gravel deposit, preparatory to dredging. There is a great difference between “cemented gravel” and “tight gravel.” A truly cemented gravel is not a dredging proposition, while the tightest possible gravel, where there is no cement, can be made easy working by the following method of blasting:

Jan 1, 2008

By Robert Hopler

RBH Note: in 1913 black powder was still dominant as a coal-mining explosive, but permissible explosives were making some slight headway. For example, in 1902 there were only 11,300 pounds of permissibles used in coal mining, but in 1913 the quantity was 21,801,285 pounds. However, there were 187,551,653 pounds of black powder used that year. It took many years before the use of black powder ended in coal mining. From the picture of the miner reparing his explosives it’s hard to tell what he’s using, but the fact that a wooden Du Pont powder box is shown, he’s probably not using black powder. That doesn’t mean he’s using a permissible, either, since that was not yet a requirement. It’s interesting that the miners have open flame cap lamps, and the miner is actually smoking a pipe while preparing his explosives.

Jan 1, 2014

By Jonathan Heiner

Rio Tinto Bingham Canyon Mine started its South Wall Push Back (SPB) in 2011. This push back will mine through the only road to the pit bottom (the 10%). The pit bottom is the main ore sector for the mine and supplies about 80 to 90% of the ore. In late 2017 the mine set off a blast in SPB that created a small wedge failure on the high wall between SPB and the 10%. This wedge failure released a rock approximately 20 minutes after that blast that rolled down the wall landing on the 10% near and then contacting a light vehicle

Jan 1, 2019

By Thierry Bernard, Jean Marc Laboz

This paper explains why and how integration of EIS (Electronic Initiation System) with dedicated software tools can increase benefits to blasters and at the same time simplify the design of blast sequence

Jan 1, 2000