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By R. Raghavaraju

Estimation of the dynamic stress field in terms of its amplitude and decay around a blast hole is a key input parameter in all numerical modeling and blast prediction exercises. However, there is very limited information available in literature on these critical parameters, which would be considered essential in any blast modeling exercise. A laboratory-scale experimental study has been carried out in two different rock types to study at very close range the stress wave decay from a blast hole at distances ranging from 3 to 10 borehole radii. The single–hole blasting experiments employed a centrally located detonating cord (5.3 g/m) in 6 mm(1/4 inch) and 10 mm (3/8 inch) boreholes. The coupling medium employed was air and water, in addition to using a thin-walled copper tube in intimate contact with borehole wall to prevent of penetration of explosion gases into the emerging cracks. The paper describes the nature (amplitude and decay) of the transmitted shock pressure and their evolution in the two rock types for these various experimental conditions, which are present to varying degrees in all blasting operations.

Jan 1, 2014

By Douglas Anderson

Even though there is always a feeling of anticipation before a blast is detonated, most blasts are part of a day’s work. Once in a while there is an event that impresses even the most jaded blaster. Few blasts have had the impact of the Kingdome implosion in March of this year. Fortunately for both the Seattle area and the explosives community, the “impact” of the implosion was far less than many local residents had feared. This outcome, of course, was not by chance, but the result of careful planning and design. An urban implosion requires a mix of engineering, logistics, and public relations. Unique challenges on this project tested the resourcefulness of the entire team.

Jan 1, 2001

By Matt Slezak, Tristan Worsey, Nathan Rouse, Kyle Hall

As everyone knows, blasters are required to file blast reports of every blast for regulatory purposes. To this day, the authors see many handwritten blast reports. Handwritten blast reports are notorious for containing errors or omissions. This is not because the blaster intends to misreport information. It is because blasters have many tasks to complete in a day, are sometimes in a rush, and could accidentally miscalculate data, omit items, or record incorrect data. In most cases, blasters do not suffer consequences to these errors because blast reports are seldom reviewed in detail. In some cases, such as when a blasting operation undergoes some sort of litigation process, the reports are reviewed in detail and the blaster is ultimately held responsible. If the reports contain errors, the blaster can be fined, have his/her license revoked, or worse. Electronic blast reporting and centralized data management can help reduce or eliminate the potential for accidental blast reporting errors to occur. This paper presents many ways that electronic blast reporting can reduce or eliminate blast reporting errors, decrease time and extra costs spent reporting, and improve efficiencies in the field and the office.

Jan 1, 2018

By E. Contestabile, R. von Rosen, R. Guilbeault, R. Fouchard, P. Lightfoot

In August 1998, a truck loaded with 18 tons of blasting explosives, including over 13 tons of ANFO, left the road near Walden, Ontario. The crash caused a fire; approximately 30 minutes later a large detonation occurred, causing substantial damage to the roadway and local property. Although nobody was injured in the explosion, the consequences of a similar incident in a heavily populated area could have been catastrophic. Following the Walden incident, Transport Canada and Natural Resources Canada embarked on an extensive experimental program to determine the cause of the detonation. This paper describes part of that experimental program, designed to understand better the thermal decomposition of ANFO.

Jan 1, 2003

By Brian W. Stump

"Seismic waves from explosions can be used to characterize physical processes in and around the source. The quantification of absolute levels of ground motion is important for minimizing impact on nearby people and structures. We contrast work in characterizing seismic radiation from contained nuclear explosions with ground motions from multiple explosion quarry blasts. A physical basedunderstanding of the explosion source function allows prediction and extrapolation to new environments where experimental data may not exist."

Jan 1, 1990

By Leon del Valle, Joe Phillips

First, I want to thank my co-author, Leon del Valle for his help and collaboration in the preparation of this paper, and also ORICA S.S. our explosive supplier and contractor at the Refugio mine site for their collaboration. The Southern Andes Mountains present a number of challenges for mining operations, and associated blasting operations. This region of the world, in Peru, Bolivis, Chile and Argentina is an area of rapid growth in precious and base metal mining, and will continue to be a large growth area for explosives products and services. This paper will attemp to discuss some of the special considerations encountered in operating a safe and effective blasting program at high elevation and under extreme weather conditions, as well as outlining a recent improvement in blasting techniques at the Refugio gold mine in northern Chile. This paper is presented from a mine operator's perspective, which may be a bit of a disappointment for some of you interested in a detailed technical review of our program. It willl, however, provide an insight in how in-pit blasting techniques tie into the metallurgical processes at a modern precious metal mine and thereby become a key elemnet in its success.

Jan 1, 2000

By Hae-Moon Choi, Sang-Don Lee, Chang-Ha Ryu

The purpose of the study presented in this article is to establish a standard blast pattern to yield optimum blasting performance along with an attempt to reduce a difference between design and construction. A series of test blasts were carried out at two tunneling sites of Central Inland Highway crossing in Korea. Long-hole blasting was tested in rock mass whose RMR value is over 60.The blasting results were evaluated by measuring degree of fragmentation, advance rate,muckpile distribution, overbreak, etc. Based on the results of test blast, several patterns were proposed for a two-lane highway tunnel.

Jan 1, 2006

By Jerry Wallace

The goal: At an industrial site, sever a well pipe containing an interior obstruction in a timely, cost effective manner by using a shape-charge to cut through the casing more than 50 meters below ground surface from the outside, doing so while inside a larger pipe, without damaging the larger pipe. The problem: Pumps and retrieval tools stuck nearly 50 meters below ground surface inside a 305 mm diameter by 9.5 mm wall thickness water well casing. The well, depth of 185 meters, had to be inspected for contaminates then properly decommissioned before industrial expansion could take place overhead. The limitations: A 508 mm diameter pipe had been driven around the 305 mm pipe to a depth of 63 meters. The usable internal diameter of the larger pipe was about 480 mm while the smaller pipe had buckled at one point forming a 350 mm wide spot. The charge thickness was limited to less than one-half the difference. Additionally, water that filled the annular space between the two pipes had to be displaced for the charge to work properly. The solution: Enlist the support of the shape-charge manufacturer to design, build and test a charge to work under the conditions present, then make it work in the field.

Jan 1, 2000

By Randall M. Wheeler, Kenneth K. Eltschlager

Blasting Seismographs use microphones to measure air overpressure from blasting. The microphone height above the ground has been the object of some controversy. The current ISEE “Field Practice Guidelines for Blasting Seismographs” specify microphone placement within 1.2 inches of the ground or over 3 feet above the ground. In this study, air overpressure measurements were taken at different height intervals and compared. Blasting seismographs constructed to the ISEE “Performance Standards for Blasting Seismographs” were used to monitor construction, quarry, and coal mine blasting. Near and far field measurements were taken to obtain representative spectral and amplitude ranges. The comparative analysis shows that microphone height has negligible impact on air overpressure measurements.1

Jan 1, 2005

By Thomas E. Brown

Commercd explosives have evolved through this century f?om dynamite through ANFO to the current lines of Water Gels and Emulsions. Water Gels and Emulsions evolved to counter the lack of water resistance and density of ANFO yet maintain its low cost position verses dynamite. Today, explosives must be safe and inexpensive and perform under a wide range of temperatures, function efficiently in wet or dry boreholes and have a good shelf life. Emulsions meet this criterion, which is why they are the current trend products worldwide.

Jan 1, 1998

By Dale S. Preece, Stephen H. Chung

Explosives energy can be used effectively in breaking and displacing large volumes of rock in mining and quarrying industries in both open pit and underground. The blast result, however, may not be economical if the applied explosives energy distribution is not properly applied to match a given set of geometries. However, this engineering problem can be resolved by using a modeling approach in the blast design process. Starting with a given set of blast design parameters that include explosive, elastic properties of rock, geometry of the blast pattern as well as the delay firing time, this paper shows how a discrete element blast model can be set up to allow the examination of the effect of critical design input parameters on blast results. Examples are given in this paper to help visualize the value and application of blast simulations. They are (1) regular and terrace bench blasting models for throw control, (2) underground blasting including a drop raise opening and (3) collapsing of a multiple room-pillar structure with proper firing sequence to control the mixing of blasted materials.

Jan 1, 2005

By Zach Ellis, Dusty Fisher

Lightning is a major concern in the explosives industry. The enormous amount of energy delivered to the Earth from a single bolt of lightning is more than capable of detonating explosives. Although explosives incidents caused by lightning strikes are rare, lightning is of great concern to blasting professionals who spend many hours working on or near loaded blast patterns.

Jan 1, 2015

By Ali Kahriman, Abdulkadir Karadogan, Deniz Adiquzel, Umit Ozer, Suat Bicer, Mehmet Aksoy

This paper presents the analysis and measurements of blast-induced ground vibrations during the construction of Istanbul Kagithane – Piyalepasa – Dolapdere – Dolmabahçe highway tunnels. These tunnels known as T1 and T2 are being constructed by a joint venture group. Within the scope of the study, the particle velocities and frequencies associated with 126 shots during the advancement of the tunnels were monitored and analyzed by vibration monitors at the test site. During the statistical analysis, three different predictor equations widely used in the literature were used to predict peak particle velocity (PPV) and the results and comparison of the predictor equations are presented in this paper. Finally, the particle velocities and frequency values of all blast events were evaluated according to USBM and German DIN 4150 Norms in order to determine the damage risks of the neighboring buildings and structures.

Jan 1, 2008

By M. Hagfors

Underwater explosions have been used several decades for the determination energy content of explosives. It’s the only test method by which shock and gas heave energy values can be determined separately. The total energy is a sum of these two partial energies. This test method enables us to develop explosives for different purposes; the military high explosives should contain more shock energy whereas the gas heave energy is a very important feature for the blasting explosives. The method also enables us to observe the changes and to adjust the energy content of an explosive as a function of increments of one or more energetic component.

Jan 1, 2006

By C. Anderson, Mike Michaelis

Ammonium Nitrate (AN) - based commercial explosives are non-ideal explosives. This is because the chemical and physical structure is heterogeneous on a distance scale comparable to, and in many cases larger than, the reaction zone in the detonating explosive. Such systems consist of inter-molecular fuel-oxidizer systems. Attempts have been made to minimize the heterogeneous nature (inter-molecular distances) of these explosives; emulsion systems are the latest examples of these commercialized AN-based explosives which balance cost, utility and performance. This latter factor (increased performance) is a direct result of increasing the contact between oxidizer and fuel.

Jan 1, 2003

By A B. Opperman

For many years explosives energy has been utilized in mining and construction as well as many other applications which are vital to our way of life. Many types of explosives have made their contribution as technology has moved forward. One of the best known was dynamite, which for many years was the mainstay of explosives users. Although dynamite had many advantages over its predecessors, it had the principal shortcomings of being somewhat hazardous to handle and was known as a headache producer.

Jan 1, 1975

By Mark A. Williams

Topography and geology greatly impact the decision of how to plan and operate a surface mine. To extract coal, five primary surface mrning methods are practiced in the United States. These include contour strip. mountamtop removal, area, modified area, and open pit mining methods. The first four approaches are commonly associated with coal mining while open pit techniques, although used in the mining of coal, are more commonly applied to the mining of hard rock, metals, and aggregates. Various sub-routines of the primary surface mining methods are likewrse applied rn the industry.

Jan 1, 1991

By Steven A. Mathe, Seokbin Lim

Current analytical models can accurately predict the final velocity of explosively driven flyers and can somewhat predict the acceleration profile, but do little to address the deformation of the flyers. Explosive systems such as linear shaped charges and explosively formed projectiles, which can be described as multiple interacting explosively driven flyers, often involve interactions between the flyers that occur much before the flyers reach their predicted final velocity. In this regime, it is important to accurately understand both the acceleration profile and the deformation profile of the flyers, as both significantly affect the functioning of the explosive systems. Previous work proposed an analytical model to meet this need. As the expanding gas cloud of detonation products drives the flyers, rarefactions impinge upon the gas cloud from around the flyer edges, which produces a pressure difference across the back face of the flyer leading to deformation of the flyer. Previous research condensed the effects of the rarefactions into a single term, the pressure release ratio, ?, which was calculated based on hydrocode simulations of a block of explosive only and an assumption of isentropic expansion. This work intends to determine the value of ? for different explosive compounds. The results of this analysis were compared to hydrocode simulations of an open-faced sandwich configuration explosive/flyer system with an average accuracy of 15% across the tested compounds.

Jan 1, 2015

By Sushil Bhandari, S. S. Rathore

Controlled drilling and blasting continue to be an important method of block production and for block splitting. Drill and blast technique has disadvantage that sometimes, it produces cracks in uncontrolled manner and also produces micro cracks in the block as well as in remaining rock, if not carefully carried out. Recovery by this method is low compared to other methods. Therefore, attempts have continued to develop controlled growth of crack in desired direction. In this paper a series of tests are described using detonating fuse in marble. Economics of different methods is also compared. In comparison to conventional use when holes are lined with inexpensive cardboard or plastic liners with a slit, the cost and damage is the least and development of crack is in desired direction.

Jan 1, 2002

By Tristan Worsey, Nathan Rouse

Florida legislature allocated funding for the Florida State Fire Marshal to review the applicability of the United States Bureau of Mines (USBM) Report of Investigations (RI) 8507 blast vibration limits with respect to Florida and its soils. The study also discusses whether the current blasting vibration limits set by statute are still appropriate, including a review of measured vibration amplitudes and frequencies, structure responses, and theoretical analyses of material strength and strains.

Jan 1, 2019