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By Alvin D. Christmas

The missing link is a connector between the congested downtown area of Knoxville, Tennessee adjacent to the former World's Fair site, the I_40 I_75, and Western Avenue traffic arteries. This connecter was designed to accommodate the 37,470 motorists who presently travel through these highly congested narrow paths to be replaced by the 21.8 million dollar Henely Street Connecter. All construction and blasting was to take place while existing traffic was re_routed so as to allow access between the downtown area and the vital interstate corridor. To avoid major traffic problems, the project was to be accomplished in three phases: (1) the Western Avenue viaduct demolition; (2) two new viaducts to be constructed; (3) the open box cut at Henely Street next to the L & N Depot. Due to the past attempts by the Fort Sanders Community Home Owners group and the Historical Society to stop the Henely Street Connector, this project involved a very comprehensive blasting damage control program with special provisions of .5 inches per second measured at the foundation of the closest structure.

Jan 1, 1995

By Xue Yongpeng, Zhu Zhenhai, Zhu Ming

The purpose of the Solid Medium Controlled Blasting Technique and Its Applications is to have the inside of the vessel-shaped framework (e.g: oil tank , water pool, gas chamber, chimney, water tower, grain warehouse and etc.) or the one side of the thin wall-shaped structure(e.g: steel bar concrete wall and etc.), both of which are intended to be demolished, inserted with the required solid medium (e.g: soil , sand , coal, salt and etc.) ,in which there is a certain mass density, and then through which the blasting energy is transferred to fulfill the blasting task. For such a technique, it is necessary to bury the explosives into the inserted solid medium and then to start the explosion to blast the intended target into pieces. The filling of the solid medium may be done mechanically or by man. Compared with the water pressure blasting technique, this one has the characteristics of good effect. wide application, simplified construction procedure , safe and reliable operation and small vibration (less vibration than water pressure blasting by 80% to 90%)in particular without any flying stones, thus resulting in better and comprehensive social and economickfficiency.

Jan 1, 2000

By Andrea Francioso, Roberto Folchi

In order to comply with the latest European Highway Standards, the highway Salerno - Reggio Calabria, in southern Italy, had do be widened and upgraded to reduce its vulnerability to earthquakes. Reinforced concrete viaducts, no longer needed for the new road, had to be demolished. Many bridges still to be used for the highway required refurbishment due to 50 years of wind, frost and salt corrosion. This re-furbishment and new construction had to be carried out simultaneously. To keep the highway open dur-ing the renewal process, all traffic was directed to one side of the road. Demolition was conducted ex-tremely close to operational roadways and viaducts, as close as only 2 cm (0.8 in). Care had to be taken to ensure that the stresses (vibration levels), resulting from the demolished pylons and decks hitting the ground, were below the no-damage thresholds for the nearby acceptors (structures receiving the vibra-tion stresses). These structures included bridges, houses and buried pipelines (water, oil and gas). In some cases, care also had to be taken to preserve the existing pylons supporting decks that were being demolished; since the same pylons were going to be used for the new viaducts (bridges). New continu-ous decks in weathering steel replaced the old reinforced concrete decks.

Jan 1, 2013

By John Tatom, Michelle Crull, Robert Conway

The US Department of Defense Explosives Safety Board is sponsoring the development of a risk-based explosives safety siting program, SAFER. The fragment and debris hazard generated at the potential explosion site (PES) is critical at an exposed site (ES) over a significant range of standoff distances. The Science Panel Impact Debris Evaluation and Review (SPIDER) test program has been planned to develop improved predictions for the hazards inside an ES by fragments and debris. Data will include the mass and velocity required for perforation of the test cross-section and the characteristics of all debris produced inside the ES.

Jan 1, 2010

By Tuan Nguyen, Dirk Hummel, Ruilin Yang

In a tunnelling site in Japan, it was found that detonators failed to initiate with their shells and primary explosive intact. Their capacitors, however, were discharged due to some damage on the application-specific integrated circuits (ASICs). These detonators are distinctly different from other commonly observed failures, where the shells are rather crashed due to excessive dynamic pressure received from neighbouring blastholes which fired earlier. Such incident has not been reported elsewhere. Detonator failures during a blast are deemed not safe and can cause disruption on the project productivity. It is therefore desirable to understand the origin of such event. Various measurements were conducted to diagnose the problem, but the root cause had yet to be identified. This paper applies a discovery from a 60-year-prior-laboratory experiment and formulates a theory that could explain the observed detonator failure and predicts the measurements and observations.

Feb 6, 2023

By Robert Hopler

SECTION 9.---BORING AND BLASTING.*155. Blasting is the operation of bringing down and detaching from its bed or position masses of material by means of explosives.

Jan 1, 2011

By Stephen Chung

The quality of a blast design can be evaluated in many ways. It may involve fragmentation, muck profile, environmental effects in terms of vibration and the excavation of the blasted material. To assist and ensure an achievable cost effective design, numerical modeling techniques are often applied as part of the operating procedure. While excavation is one of the mining operations which has a direct influence on the bottom line cost of productivity, the characteristics of a pile of blasted material deserves a closer look in terms of diggability. This paper reviews the current diggability techniques available for application to the blasting operation. To help better understand the involvement in digging, this paper also introduces an evaluation approach based on a discrete element method. The model presented in this paper deals with many variables that are considered to directly affect digging. They are the density and cohesion of material, fragment shape and size distribution as well as the swell of a muck pile. To help visualize the analysis approach, sample runs and animations are given in the paper to show the setup of muck piles produced in bench blasting as well as in sub-level caving. The computed forces experienced by the bucket during each mucking cycle are also discussed.

Jan 1, 2008

By Favreau R. F. Ph. D, Favreau Patrice

The article explains that the way to achieve a successful blast is by insuring that the explosive energy divides properly into the weakening action of the shock wave which is necessary to prevent large collar blocks and toe, and into adequate stress field intensity SS which is necessary to obtain good fragmentation size distribution at the crusher, as well as adequate burst out rock movement to achieve easy mucking.

Feb 1, 2020

By Edward Fitch

The DOE is evaluating Yucca Mountain, Nevada as a potential site for disposal of high level nuclear waste. Yucca Mountain is located approximately 160 km northwest of Las Vegas on the western edge of the Nevada Test Site and the Nellis Air Force Range. An exploratory tunnel has been constructed through Yucca Mountain for site characterization. A controlled drilling and blasting technique, smooth wall blasting, was used to excavate the TBM starter tunnel and alcoves off the main tunnel to provide areas for scientific investigation. Fundamental to the blasting program has been the use of two blast design equations used in concert to minimize blast damage to the surrounding rock mass. The first of these equations was developed by Roger Holmberg and estimates near-field peak particle velocity that is the basis for minimizing blast damage to the host rock. The second of these equations was developed by B. H. Sanden and provides bore hole pressure estimation which allows controls to minimize crushing of the rock mass along the perimeter yet allowing enough force to create tensile failure between perimeter bore holes. This is key to the smooth wall blasting technique. To date, essentially the same controlled drilling and blasting program has been in place for all excavation requiring controlled drilling and blasting at the ESF. The controlled drilling and blasting program uses an iterative process to achieve continuous improvement in the blast rounds. This involves interaction between Architect and Engineer (A/E), Constructor, and Testing Coordination O&e (TCO) to ensure each blast round successfully meets the expectations of affected participants. The A/E requested that the TCO provide validation of the near-field peak particle velocity estimation under the Construction Monitoring Program. Data gathered under this program were reduced by statistical analysis and used to verify blast design parameters and provide a site specific blast damage relationship.

Jan 1, 2000

By María Virginia Ramírez, Alejandro Alarcón, Alea Reyes

Reactive grounds (presence of FeS2, CuFeS2) can create hazards in a mine; misfires to premature deflagration or detonation of loaded blast holes. This occurs because some minerals can react to ANFObased explosives. Due to a high potential event that occurred in The Mine in 2013, The Mine and the Explosive Provider (“The Company”) are conducting a soil characterization of the areas containing reactive sulfides. This study was planned along with The Mine and it is being developed by a multidisciplinary team.

Jan 1, 2018

By David Jones, Jeff Bregar, Damien Bell

We have analyzed overpressure and ground vibration measurements for construction blasting for a large pipeline project. These field-measured levels have been compared to existing prediction curves in the literature and new curves have been proposed for overpressure and ground vibration for pipeline construction blasting activities.

Feb 1, 2020

By Richard Mainiero, James H. Rowland III

For many years there have been small scale tests available for evaluating the toxic fumes production by capsensitive explosives (DOT Class 1. l), but these could not be used with blasting agents due to the large charge sizes and heavy confinement required for proper detonation. Considering the extensive use of blasting agents in construction and mining, there is a need to determine the quantities of toxic ti,tmes generated by blasting agents. At the International Society of Explosive Engineers Twenty Third Annual Conference on Explosives and Blasting Technique in 1997, the authors reported on a facility for detonating large (4.54 kg), confined blasting agent charges in a controlled volume that had been constructed at the National Institute for Occupational Safety and Health’s Pittsburgh Research Lab’s Experimental Mine. Since 1997, this facility has been used to collect data on toxic fumes produced by the detonation of various ammonium nitrate/fuel oil (ANFO) mixtures and several cap-sensitive explosives. ANFO composition ranging from 1 to 10 percent (pet) tieI oil have been studied. As expected from previous studies, with an increase in fuel oil content the carbon monoxide production increases, while nitric oxide and nitrogen dioxide production decrease. The detonation velocity varies from 3,000 to 4,000 m/set for the 1 to 10 pet range of fuel oil content, suggesting that ANFO mixes with improper fuel oil content may appear to detonate properly, while their fume production differs significantly from optimum. The study also considers such factors as degree of confinement, water contamination, and aluminum content on blasting agent fume production. Results indicate that water contamination of the ANFO has little effect on carbon monoxide production, but causes significant increase in nitric oxide and nitrogen dioxide production. Decreasing confinement from Schedule 80 steel pipe to 0.4~mm thick sheet metal also has little effect on carbon monoxide production, but significantly increases nitric oxide and nitrogen dioxide production. Adding 5 and 10 pet aluminum to the ANFO had no clear effect on carbon monoxide, nitric oxide, or nitrogen dioxide production.

Jan 1, 2000

By D. Johansson, C. San Miguel, U. Stenman, N. Petropoulos

Blasting is a commonly utilized method in civil engineering projects and mining operations. Ammonium nitrate-based (AN-based) explosives are the most efficient explosives today in terms of handling and performance. However, a side effect is the production of gases. The reduction of these gases plays an important role in the safety and environmental aspects in the working place. Therefore, optimizing the recipes of explosives is vital for minimizing the environmental impact and increasing performance. The aim of the project is to provide results and recommendations on the use of emulsion commercial explosives to support the Swedish mining industry and tunnel-contractors as well as the explosives manufactures. The approach was to test various recipes of civil emulsion explosives to investigate the generation of toxic fumes (CO, CO2, NO, NO2 and NOx) during their detonation. To further increase the knowledge of the influence of different additives, ammonium nitrate prills were added in various percentages. The experimental configuration consisted of magnetite mortar cylindrical specimens with a 50 mm borehole at their center, filled with emulsion explosive. Several tests with different emulsion compositions regarding ammonium nitrate additives (10%, 20%, 25%, 30% and 35%) were carried out in a blasting chamber. The measurement equipment was composed of a flue gas analyzer. The instrument was meticulously cleaned after every test, as well as before and during the tests due to condensation (high humidity and dust) at the inlet of the instrument. The emulsion was manually sensitized with microballons and pumped into the cylinders to ensure lack of bubbles, which could introduce inhomogeneities. The acquired gas concentration data was complemented with temperature, humidity, and VoD measurements. The results showed a linear increase of nitrogen gases as the percentage of ammonium nitrate prills increased. On the other hand, carbon gases had a relatively low coefficient of determination. The VoD data showed a behavior that can be described with a simple quadratic equation.

Jan 1, 2024

By Lon D. Santis

This paper describes a lightning warning system (LWS) in operation at the U.S. Bureau of Mines' (USBM) Pittsburgh Research Center (PRC) from December, 1989 to April, 1991. An electric field mill measured the DC atmospheric electrostatic field. Also, an economical on-line weather data service provided lightning location maps and other weather information. A system such as this can significantly improve the safety of explosive handling. The use of these two methods addresses the detection of thunderclouds building overhead and the prediction and tracking of developed storms. Warning reliability of the system was very good when data from both sources were considered. Experience showed, however, that use of either system alone would not provide adequate reliability in most situations. Some problems occurred with the field mill and there is some question whether the instrument is compatible with harsh mining environments or could be made portable. Another method ' of measuring electric field based on fiber optics is discussed. This technology may be able to overcome the problems with field mills.

Jan 1, 1993

By Emily Johnson, Catherine Johnson, Rachel Bauer, Paul Pitzel

Demolition projects involving explosives may incorporate cutting charges to sever columns in collaboration with kicker charges that “move” the columns out of alignment. Traditional kicker charges often involve the use of dynamite secured to the column above the cutting charge. Nitroglycerine, the main component of dynamite, causes medical problems and can be a hazard to workers on site. Dynamite can also cause fragmentation of the column and structures, resulting in potential injuries to people or leading to the possibility of cutoffs in neighboring charges. This study investigates the use of water-cased kicker charges to reduce the amount of dynamite in demolition. Water charges, traditional charges, and detonating cord charges were placed on hanging steel columns and analyzed for the fragmentation of the column and velocity of the column. A W 10 X 22 beam was hung in an underground limestone test area and allowed to swing freely acting as a severed column. Charges were attached to the bottom of the column with tape and initiated using electric detonators. Explosive charges of dynamite or detonating cord were placed in the center of a water container or directly on the column for use as the kicker charge. Tests were recorded with high-speed video and velocity was calculated using Phantom Camera Control software. Velocity and time were then used to calculate force, kinetic energy, impulse, and pressure exerted by the explosive on the column. The water charge transferred energy to the column over a larger area with no direct contact of explosive and the column. Water charges moved the column faster and with more power than traditional charges. After preliminary tests, water charges were also used as the primary kicker charges in a full-scale demolition project as a case study using 118 charges. The kicker charges successfully moved building members without creating fragmentation while using less dynamite than traditional kicker charges. Due to the success, multiple full-scale projects are being designed using water charges to show success and repeatability.

Feb 6, 2023

By Pavel A. Torres, Darwin Torres, Sandro Huaman

Given the limited efficiency of blast-induced ground vibrations prediction empirical models, due to the complex geological system from a Peruvian mine. An artificial neural network was built in order to get better results. More accurate and precise predictions allowed the generation of blasting domains for future designs and decision making.

Feb 1, 2020

By N. Paley

An engineering project was undertaken at the Cominco Alaska Red Dog Mine to determine the extent that Semi-Autogenous Grinding (SAG) mill throughput could be increased by blasting differently. The Julius Kruttschnitt Mineral Research Center (JKMRC) blast fragmentation, jaw crusher, and SAG mill breakage models were used to relate changes in the blast design to the SAG mill performance. For optimum performance a SAG mill requires a particular size distribution; a number of large rocks to facilitate breakage by impact, as few as possible middle size rocks that become critical size, and the maximum fines which will pass quickly through an open-circuit mill. Physical constraints of drill and charging equipment size limit the extent that pattern geometry can be changed and the powder factor increased to maximize fines. However, JKMRC research had shown that it appeared possible to increase primary breakage by blasting to such an extent that SAG mill throughput could reach a plateau or even begin to decrease. Modeling was carried out on a range of blast pattern geometries and emulsion explosive blends to determine if a plateau existed and at what powder factor it would be reached. It was found that the relationship between powder factor and grinding throughput was nonlinear. Modeling was also used to compare the SAG mill throughput which could be expected from different emulsion explosive blends to determine which blends should be used in dry and wet holes to provide similar fragmentation. For heavy-ANFO mixtures, the highest modeled throughput was at a ratio of 30/70, with ratios on either side indicating lower throughput. For emulsion blends, the highest modeled throughput was at a ratio of 80/20; however, ratios from 80/20 to lOO/O were similar. Crusher product size distributions were obtained from belt cuts early in the analysis to confirm model predictions. At later stages, actual SAG mill throughput was compared to predicted. The economic benetit from the different blast designs was calculated by accounting for the reduction in recovery due to the higher throughput and the additional drilling and blasting costs. Increasing the powder factor by 150% from the 0.29kg/t {0.58lb/st] being used to 0.72kg/t { 1.44lb/st}, the maximum feasible with mine equipment, could provide a sign&ant net benefit of $3OWyr due to the increased concentrate production. However, because the relationship between throughput and recovery is affected by other factors which were not modeled, a more conservative approach was taken. The powder factor was instead increased by 50°h, providing 45% of the gain. This was possible because the relationship between powder factor and grinding throughput was nonlinear.

Jan 1, 2001

By Grant Small, Deon Pieterse

Reactive ground conditions at an open pit manganese mine in the Northern Cape of South Africa resulted in an unexpected detonation.

Feb 1, 2020

By Julio Cesar Barbosa de Freitas, Rafael Gonçalves Araujo, Túlio Soares, Jair Koppe, Augusto Ferraz Ribeiro, Pedro Barreto Garcia

This study thesis was motivated by the fact that it is of fundamental importance for open pit mining that the slopes initially have a geometry in accordance with what is proposed in the mining planning. This occurs because an inconsistency in this design can impact the operational safety and economic solutions of the mining project. These consequences can be explained by the fact that rock blasting close to mining limits requires specific study due to the attention required. Because, when this operation is not carried out properly, the mining plan in the mine may not be respected and may create risks to the operation due to the presence of unstable blocks on the slopes (Mackenzie). In this sense, Mackenzie (2004) cites pre-split, trim blasting and buffer as commonly used explosive blasting techniques that aim to limit damage beyond the projected wall. Therefore, Enaex Brazil realized the need to better understand the pre-split method. To do this, it is necessary to understand how the energy released during detonation is perpetuated in the rock mass when this technique is used and when it is absent. Thus, this analysis is based on a seismic study that allows the creation of vibration attenuation laws and an elementary wave damage model, which allows the local characterization of the rock. With this model it is possible to relate the peak levels of vibration during blasting and the extent of damage, but a critical level of vibration (PPVc) and its relationship with the Uniaxial Comprehension Resistance (UCS) are also defined for the start of fracturing and its level (McKenzie et al, 1995). And, mainly, this work aims to address a way to measure the pre-split filter potential by comparing the attenuation law with and without pre-split, ultimately knowing whether this finishing blasting is being effective, to understand the pre-split filter capacity.

Jan 21, 2025

By W. Birch, G. D. Rangel-Sharp, L. Bermingham

For many years, the accepted method of Measuring the Velocity of Detonation (VOD) in blast holes has been to use an electric cable of a constant resistance per metre. Thus as the wire is consumed by the explosive in the blast hole, the change in resistance is monitored and when this data is plotted against the time period of the in hole explosion, the VOD can be calculated.

Jan 1, 2011