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By S. J. Dillingham

One of the primary goals of every blaster is to achieve the optimum blast design. Too much focus on efficient design, however, can cloud certain issues and exposures that must be addressed if the entire project is to be considered .successful.. Due to the known human response to blast effects and inherent dangers present in the use of explosives, the potential for the project being delayed or shutdown, or the blaster and associated company being named as a defendant in a lawsuit, is always a possibility. Therefore, the blast design and associated project bid must incorporate sound safety contingences and procedures that address those .what-if. Scenarios that may arise as a result of vibration, flyrock, public relations, and job-site personal safety.

Jan 1, 2002

By Michael S. Wieland, Thomas C. Ruhe

Delay blasting in underground coal results in shock waves traveling through the coal that can damage delay charges remaining in the blast pattern. Undetonated explosives which are dynamically desensitized or react sympathetically from shock wave impact ruin blast results. Such malfunctions, sometimes manifest as misfires, more frequently are covert weak detonations, and result in poor coal breakage and fumes with above normal toxicity. To reduce these mining hazards and resolve charge performance problems, the Bureau of Mines has developed and tested forty prototype rugged explosives in the laboratory. Rugged explosives work properly under difficult circumstances because they not only retain their shock initiation sensitivity but also are resistant to shock damage. This research investigation resulted in one candidate emulsion explosive, formulation #37, which passed all the permissibility tests required by MSHA approval regulations. However, approval was not granted because it reached shelf-life (would not shoot properly) seven months into testing. For research purposes, the remaining tests were conducted with a second batch of formulation #37. This paper discusses the prototype rugged explosive composition and permissibility test results. Where possible, for reference purposes, comparisons are made to a commercial product that has been approved. Further research work is required to overcome the noted deficiency of short shelf-life.

Jan 1, 1992

By Frank Wilder, Mark Ferrero

One of the challenges currently facing the explosives industry is how to transition its workforce and its business systems to respond to the increasing pressures for improved inventory and records management. The pressures applied by many U.S. federal and state agencies, such as the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) and the Department of Environmental Protection (DEP), as well as regulatory agencies around the world, are increasing the need for accurate inventory accounting of explosive materials and blast documentation. With blasting companies now facing regular documentation audits, potential liability issues may arise due to the inconsistent or missing documentation.

Jan 1, 2006

By Per-Anders Persson

TIGERWIN, now on CD, is a user-friendly personal computer code (running under Windows) which determines the detonation and expansion state of an explosive from its known chemical composition. TIGERWIN is intended for users in the mining and commercial explosives industry who do not routinely program or run Fortran codes. The code allows the user to open a window on the computer screen and enter the initial density and the weight percentage composition of an explosive, ingredient by ingredient. Alternatively, the code can balance the composition with one or more ingredient percentages fixed, while proportionally adjusting the others automatically to give a total of 100%. The equation of state and its parameters can be user-selected from several proven and tested versions of the BKW, the JCZ, and the ideal gas equations of state. TIGERWIN allows the user to select several options for different additional calculations, such as determining the constant volume explosion, the Chapman-Jouguet (C-J) point, the detonation Hugoniot, the expansion isentrope from the C-J point, and point calculations with selectable specific volume and temperature. Additional options include calculations of detonation data with one or more ingredients partially reacted, assuming either temperature equilibrium between reaction products and unreacted material, or keeping the unreacted material “cold” at the initial temperature. Thus the code can run both ideal and non-ideal detonation calculations. The code automatically saves the input and output files in a separate directory for future reference. The output from several calculations can be displayed and printed in the form of a comparison table. In it, the key results of up to five calculations with different explosive compositions can be compared. The results from an individual calculation can be displayed graphically and printed with expansion work, pressure, or temperature as functions of specific volume. A complete listing of the details of the calculation results, similar to those from the original Fortran Tiger calculations, can also be displayed and printed. No computer experience is required to run the code and workshop participants are encouraged to bring in their own formulations to try out on TIGERWIN

Jan 1, 2000

By Abraham Lindo

Panama’s current economical growth demands an increase in electric power supply; projected energy supply for 2012 exceeds the demand by as little as 2%. In an effort to comply with the demand, several different hydroelectric projects, promoted by the government, are currently under construction and each of them vary in generating capacity, construction design and complexity.

Jan 1, 2013

By Sri R. B Singh

Based on CMRI investigations in nearly 50 mines, the authors have developed two empirical formulae for the effective determination of burden and spacing in any kind of rock deposit. Along with charge loading parameters, decoupling effect and bench height, the equations consider rock characterisation parameter by incorporating 'RQD' i.e Rock Quality Designation. The value of 'RQD' may be obtained either by core recovery using diamond drilling or theoretically from the characteristics of joints or bedding planes. The derived equations may be used in any rock mass under varying geologic and charge loading conditions. The Formulae suggested herein, are explicit, simple in form and easily applicable in field purposes. The values obtained from the present equations are verified against various field data generated by CMRI during the past several years.

Jan 1, 1998

By Chang-Ha Ryu, Hyung Yang, Hyung-Sik Yang

Ground vibration by rock blasting causes many environmental problems to adjacent structures and human bodies. Growing concerns have been given to the effects of dynamic loading induced by blasting works near safety-related structure like nuclear power plant, hospital, broadcasting station, research institute and tish farm, etc. In order to ensure the safety, rational safe criterion should be established. It requires development of a model to predict the design parameters through more systematic measurement and analysis. Primary estimation by adequate model with general parameters will be very useful for safe design and understanding the possible hazards in advance.

Jan 1, 2001

By Mark S. Stagg, David E. Siskind

The Bureau of Mines arranged to have a wood-frame test house built in the pat of an advancing surface coal nine so it could investigate the effects of repeated blasting on a residential house. Structural fatigue and damage were assessed over a 2-yr period. The house was subjected to vibrations from 587 production blasts with particle velocities that varied from 0.10 to 6.94 in/s. Later, the entire house was mechanically shaken to produce fatigue cracking. Failure strain characteristics of construction materials were evaluated as a basis for comparing strains induced by blasting and shaker loading to those induced by weather and household activities. Cosmetic or hairline cracks 0.01 to 0.10 mm wide occurred during construction of the house and also during periods when no blasts were detonated. The formation of cosmetic cracks increased from 0.3 to 1.0 cracks per week when ground motions exceeded 1.0 in/s. Human activity and changes in temperature and humidity caused strains in walls that were equivalent to those produced by ground motions up to 1.2 in/s. When the entire structure was mechanically shaken, the first wallboard tape joint crack appeared after 56,000 cycles, the equivalent of 28 yr of shaking by blast-generated ground motions of 0.5 in/s twice a day.

Jan 1, 1985

By R Deshaise, B Mbhanty

The importance of controlling density of commercial explosives, and the various means to achieve it are described. m e field conditions responsible for density changes during blasting and their effect on blast results are examined. Understanding of the behaviour of density control ingredients such as gas bubbles, glass and plastic microballoons under pressure, is considered essential to predicting explosives performance. Both static and dynamic pressure effects have been studied for typical donor-receptor cartridge configurations. The amplitude and temporal characteristics of dynamic pressures inside receptor explosives have been studied by means of the underwater test, and guidelines developed to limit density changes due to external pressures.

Jan 1, 1989

By J Deen, P Sterk, W Forsyth

Homestake Mining Company has made a firm commitment to develop a functional and cost effective perimeter blasting program. The goal of the program is to develop smooth, sound walls in all development ends. A good perimeter blasting method will improve safety, reduce waste rock handling, allow easier support installation and reduce scaling time. All the benefits will contribute to an overall reduction in total development costs.

Jan 1, 1997

By Calvin Konya, Steven S. Spagna, Ed Smith

During Summer 2001, the U.S Army Corps of Engineers awarded a contract to the construction firm of Bush and Burchett of Allen, Kentucky, for the purpose of developing a 13 acre redevelopment site by removing approximately 2.5 million cubic yards of rock (fig. 1). The Redevelopment Site will be the future home for a large portion of the City of Grundy, Virginia. Additional work items include the construction and relocation of 3,000 feet of the Norfolk Southern railroad bed, the placement of 95,000 cubic yards of fill and the placement of 16,000 cubic yards of stone slope protection along the Levisa Fork River. Bush and Burchett received a notice to proceed with construction in July 2001. Currently, the contract is near completion. Current activities include: hauling of material from the Redevelopment Site to the disposal area; placing fill material on the Redevelopment Site, and placing Stone Slope Protection (SSP) along the Levisa Fork river. Approximately one year into the construction highly weathered rock, degraded to near soil- like condition, was encountered in the upstream portion of the excavation. Over one-third of the original cut slope was adjusted and the blasting specifications had to be amended to accommodate for the material that was encountered in this area.

Jan 1, 2005

By Jody Todd, Ernesto Villaescusa, Ronald Lachenicht, Kelly Fleetwood

In the underground environment, characterisation of a rock mass during the mining cycle becomes increasingly difficult due to a lack of rock mass exposure for measurement or observation. In most cases rock mass characterisation occurs prior to mining by inspection and logging of exploration drill core, or prior to mass excavation through drive mapping for geological and geotechnical data. Characterisation strategies, if applied during the mining cycle, can reveal near-field anisotropies that may affect the behaviour of the rock mass with respect to excavation. These methods can aid in understanding the performance of stopes based on geometry, in-stope extraction sequence, and stress modelling. One such method of characterisation involves the use of production blast vibration monitoring and analysis as indicators of rock mass anisotropy through travel-time tomography.

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 Jhon J. Silva Castro

Blast vibration records used in mining contain unwanted information in the form of noise due to long-period drifts, background noise, and noise due to the conversion of the analogue signal to a digital signal. When recorded signals from blasting are used to find other physical variables, such as going from particle velocity to acceleration or displacement, the additional information in the vibration signal can result in inaccuracies in the estimation of the peak values and more dramatically, the results in displacement or acceleration can be nonzero near the end of the record. There are different proposed methods to clean or filter the unwanted information from the signal. All of the methods are based on finding the best fit of the record average value (baseline) and then subtracting from the record under analysis to produce the desirable adjustment. Different criteria and functions are used to define the best fit. The function to use will depend on the shape of the record average values. The main characteristic of the baseline function is that it represents a low frequency wave. Such a low frequency wave can be a periodic function or a polynomial expression of nth order. According to the order of the polynomial expression, the baseline correction can be linear, parabolic or high order. In this document the detailed procedure and the results for the baseline correction of a blast vibration record using a periodic function and a polynomial expression of different order is presented. The results show that the drift problem when displacement is calculate using velocity records increases with the increase of the distance from the blast.

Jan 1, 2015

By Byron Groen, Corry Goumans

Description of Project: Project location is at WAC Bennett Dam in Hudson’s Hope, British Columbia, Canada.

Jan 1, 2014

By David W. Zeeb

The use of an ordinary VHS video camera and a four-head player can be an effective tool to analyze surface blasting. The necessary equipment can be purchased for under $1,300 and will allow frame by frame or slow motion viewing of a blast in 33.33 millisecond increments. Rock breakage, movement, and timing can be studied in high quality slow motion. These studies can result in improved blasts by showing things that the eye can miss in real time.

Jan 1, 1992

By Thomas Leonard, Philip R. Berger, Bryan E. Papillon

Bardon Trimount Inc., a large producer of aggregate, crushed stone, and concrete, was experiencing significant public opposition to its five quarries in the Boston area. It was believed by the authors that this opposition could be significantly lessened if the total number of blasts per week were reduced. Although the blasting company at these quarries, Austin Powder Company, contended that this could easily and safely be accomplished by increasing the size of the blasts, regulations precluded this alternative by limiting the total amount of explosives that could be used per blast.

Jan 1, 1996

By Florian Bauer

The Fording River mine in British Columbia produces hard coking coal in an open pit operation. Coal seams are exposed by blasting overburden and digging blasted muck with rope shovels. The drilling and blasting process presents a considerable cost factor to the operation. Reducing the amount of explosives needed therefore contributes considerably to costs saving initiatives. However, reducing the powder factor only makes sense if the subsequent loading processes by the shovels are not compromised in terms of productivity.

Jan 1, 2014

By Ignacio Humeres Valdivia, Alejandro Ferrada Vergara

In the latest years, the use of innovative blasting techniques has become more frequent in mines all over the world. Such techniques allow the miner to be more aggressive in the distribution of explosive energy into the rock mass, e.g., stretching blasting patterns to improve fragmentation. Considering the different rock mass conditions and more energetic blasting designs, misfired shot events have occurred. After cause investigation, initiators have shown evidences of deformation by impact and/or loaded boreholes have resulted in emulsion desensitization, both presumably affected by dynamic pressure.

Jan 1, 2015

By Ron Woolf, Corry Goumans

With increasing traffic volumes experienced thro u g hout North America, a common goal for Highway officials is to keep traffic flowing as much as possible and to keep disruptions to the flow to a minimum. Our experience throughout the US and Canada has shown that all Departments of Transportation are under extreme pressure from the private sector to keep highways open for various reasons, convenience and revenue being the most common. For example, on Highway 99, from Vancouver, BC to the Whistler resort area, local merchants, homeowners and ski hill operators exert extreme pressure on the Ministry of Transportation to keep the highway open, and in Pennsylvania, the Turnpike Commission requires traffic to flow on a continual basis. Loss of revenue in these two cases is the main impetus to keep the traffic moving.

Jan 1, 2003