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By John C. Didlinger, John L. Didlinger

As we begin the pre-blast survey we need to decide on the number of holes needed for production and a detailed highwall inspection. The survey consists of checking the highwall and placement of barrier cones. At the Elmhurst Chicago Stone Company, Barbers Corner Plant, we use 18-24" orange highway type safety cones. These cones are easily noticed because of their high visibility color in all weather conditions and are placed approximately 20-25 feet from the face and approximately 50 feet apart along the highwall, then the area is checked for back break, under cut, over hang, surface filled area and clay area. This deposit is unique because of the number of clay filled areas and slip seams that meanders through the deposit plus a fault that runs North-Northwest and South-Southeast. This particular limestone deposit is overlaid with glacial sand and gravel and the top weathered stone wanders plus or minus 10 feet in 1400 feet.

Jan 1, 1996

By Clive-Workman Davies, K K. Kabongo, Mensah Frimpong

Given the capital intensity of the dragline operation coupled with rising cost of explosives, the onus is on mine operators to make maximum use of explosives in blasting to assist dragline diggability. At a surface coal mine in South Africa large boulders necessitating secondary breakage and in some cases completely unfragmented sections of a blast resulting in low dragline diggability were encountered in the interburden blast. Twelve blasts were therefore closely monitored and dragline productivity evaluated. The ultimate aim was to improve the overall blasting performance and hence increase dragline productivity. Three areas were in focus; fragmentation assessment, dragline productivity assessment and cost analysis. The studies indicated unsatisfactory explosive and initiation performance, problematic blast design and questionable operators performance. It is established that dragline cost account for 60% of the total mining cost whereas the drilling and blasting cost account for the remaining 40% and that improvement in dragline productivity results in automatic cost saving.

Jan 1, 1996

By Dean E. Albon

The author gives a brief resume of his observations of drilling and blasting supervision in surface coal mines during the past thirty years and recommendations for upgrading this supervision to the category of a professional.

Jan 1, 1979

By Bruce B. Redpath

This paper reviews empirical and analytical information about window breakage due to airblast. As is the case with damage to structures caused by ground vibrations, a fixed break/no break threshold is inapplicable and window damage must be expressed in terms of a statistical probability. The information is summarized in a graph showing the probability of windows being broken by a given level of overpressure.

Jan 1, 1976

By R Keller, R Law

In the rush to beat the clock before the handover of Hong Kong back to China in June of 1997, an unprecedented amount of infrastructure work is being undertaken at a breakneck pace. In the middle of this construction explosion, on this island of barren granite , stands some of the most concerning and restrictive slope stability measures. So conservative, these measures impact blasting and vibration control to an extent unmatched anywhere in the world.

Jan 1, 1996

By Francis O. Otuonye

A time series and system analysis modeling technique was applied to signals from strain egages mounted on a fully grouted resin roof bolt and signals from accelerometers mounted on the bolt head and roof rock to determine the roof bolt's response to repeated blast loading. The derived model gives a comprehensive quantitative description of the modes of vibration of the roof bolt response to each blast loading. The damping ratios and natural frequencies of the modes of vibration can reveal the alteration of the process dynamics due to the deterioration of the roof rock and can be used to identify the incipience of instability in the roof bolt system.

Jan 1, 1987

By Mark S. Stagg, Rolfe E. Otterness, Stephen A. Rholl

The Bureau of Mines fired seven test blasts in a 22-ft bench of limestone, screening the material to investigate the influence of explosive type and between row delays on fragmentation. Four 4-hole, single-row test shots were conducted evaluating dynamite, ANFO, emulsion, and a 60-40 emulsion-ANFO mix. Three 12-hole shots, with three rows of 4-holes, evaluated delays between rows of 24, 36, and 120 ms. Accurate in-hole electronic delays were used, firing within 1.5-ms of the nominal delay. All seven shots had a 6- to 7-ft burden, 10-ft spacing, with a hole diameter of 3-1/2 in fired on a 12-ms delay between holes in the row. The tests were instrumented with strain gauges grouted in the burden region examining stress wave and gas pressure effects. Fiber optic probes were used to confirm timing and to obtain detonation velocities.

Jan 1, 1989

By N K. Jain, Rajesh Jain

This article has been written indicating the present trend in Blasting all over the World, so as to help in planning production and development of Industrial Explosives for the development of industries in all the countries in general

Jan 1, 1992

By Jay P. Tobin

This paper will address the legal standards applicable to construction blasting lawsuits and offer best practices suggestions for pre-blast inspections, documenting the construction blasting work, recordkeeping, and effectively participating and partnering in the defense of a construction blasting lawsuit.

Jan 1, 2015

By D Larson, M Finger

Chemical explosives may become a key element in many of the in situ energy and mineral recovery methods under development. This paper discusses the potential role of explosives in deep rock mining for resource recovery. Several energy and mineral recovery programs described are an outgrowth of the Plowshare Program and Explosives R&D conducted as part of the AEC/ERDA mission at Lawrence Livermore Laboratory. Several important aspects of the use of explosives in deep rock mining are reviewed. First, the status of knowledge of deep rock fracturing to create permeability underground is discussed. Completely contained blasting has not been a widely applied tool used in the mining industry. We conclude that data available on deep rock fracture is minimal and that the mechanisms that control the processes must be understood before technical and economic feasibility can be established. We also discuss the unusual problems in the selection of an explosive or blasting agent for deep rock applications including emphasis on the functioning at depth and safety aspects. Finally, a brief review of similar activities within the U.S. is given.

Jan 1, 1976

By Larry R. Fletcher

Excessive flyrock, which is blasted rock that travels beyond the secured blast area, is responsible for 25 pct of the blasting injuries that occur in surface mining. Excessive flyrock is also a frequent cause of damage to mine equipment and facilities.

Jan 1, 1986

By Cameron McKenzie

Flyrock is a complex issue involving interaction between the charging crew, the blast design, and the local geology, and once conditions on the shot meet certain criteria, the probability of a flyrock incident becomes unacceptably high. It is essential that flyrock awareness be built into the blast design process, requiring an engineering approach to understanding and controlling the outcomes and managing the associated risks. Based on previous studies of flyrock and published literature relating to fragment motion at high velocity in air, the equations to predict maximum flyrock range, and the size of particle achieving the maximum range, for blasts of varying rock density, hole diameter, explosive density, and state of confinement have been developed. These equations, and other associated correlations, permit the flyrock footprints to be established for any charge configuration, in any size blasthole, in rock of any density, and with particles of any known shape factor. The equations developed, and the mechanisms they reflect, allow engineers to go a long way towards understanding the primary factors controlling flyrock generation, including the rock mass, the blast design, and the quality of blast design implementation, i.e. the human factor. The paper presents guidelines as regards use of the equations to establish personnel clearance distances as a function of charge design and implementation, and equations to estimate appropriate stemming lengths when blasting must be conducted close to occupied or sensitive structures. The equations are amenable to definition of, and quantification of Flyrock Risk.

Jan 1, 2009

By Owen Collins

In surface mining, designing patterns to reduce the probability of flyrock and optimizing fragmentation through powder factor calculations are important for safe, efficient blasts. The designed powder factor is established for the blast once parameters such as burden, spacing, stemming, and powder column height are determined. In practice, these parameters are usually constant throughout a production blast with row-to-row burden and spacing. However, challenges can arise with the introduction of an open face. Many variables could necessitate the adjustment of the face row to optimize blast results. Variables include drill accessibility, challenges with toes, overhangs, and geology. The approach is often, but not exclusively, determining how to keep a consistent powder factor from the open face through the body of the blast. However, the solutions used vary case-by-case and rarely are two blasts the same. Technology has improved the ability to deal with challenging face conditions. 3D modeling with the aid of drones allows the application of angled holes to be more effective and simpler. This is just one instance where technology has improved blast results. This paper will present solutions to challenging face conditions. Thoroughly analyzing instances where challenging open-face variables were met with an effective blast solution could help provide insight as to what yields consistent blast results.

Jan 26, 2026

By Leslie Taylor, R. Reed Skagga, William Gault

The ultimate aim of our overall task, of which the effort described in this paper is a part, is to be able to model the impulsive output of buried charges and the response of targets of interest. It is not practical or cost-effective to determine the response of all targets of interest to buried charges of all sizes by testing them. In order to have confidence in our models, however, they must be validated by a modest number of tests. A critical element in modeling the response of a target is the ability to model the loading function. The load a buried charge applies to a target above it when the charge detonates can be characterized in terms of the vertical impulse. The vertical impulse is a function of the size of the charge, its depth of burial, and the properties of the soil in which it is buried. The primary objective of the effort described in this paper is to determine the load a known charge places on a non-responding target so the data can be used to validate our models.

Jan 1, 2005

By Robert A. Farnfield

This paper outlines the theory behind transfer functions and illustrates their application in the prediction of structural response to blast induced ground vibration. The ability to predict the response of a structure to a recorded ground vibration is desirable for a number of reasons.

Jan 1, 1994

By R. Wharton, M. Bagley

Following a series of papers relating to the certification of explosives for sale in member states of the European Union presented at previous ISEE conferences, this poster paper has been prepared to stimulate discussion and debate on the recently published European Directive on Pyrotechnic Articles.

Jan 1, 2008

By P D. Katsabanis

The phenomenon of sympathetic detonations in blastholes is investigated by comparing experimental observations and numerical modelling results. Numerical modelling using the TDL computer code and Forest Fire decomposition rates for commercial explosives has shown the importance of blasthole diameter, impedance of stemming material and host rock. Comparison with experimental observations has also shown that sympathetic detonations cannot always be treated as shock to detonation transitions (SDT). Examination of previous results which have been obtained from calibrated low amplitude shock experiments reveal that there is an ignition threshold prior to the detonation threshold. The difference between the two thresholds is more pronounced in the case of air bubble sensitized products. The ignition threshold can be very important under the confinement provided by the blasthole and the conditions of application. It also correlates well with the pressures expected at the gap distances of interest in the practical application. It is suggested that critical energies are used as the criterion for cross initiation in blastholes. Practical suggestions based on the numerical calculations and experiments based on these calculations are also given and discussed.

Jan 1, 1992

Vibrations are of concern not only for the safety of surface structures but also for the stability of underground openings. A number of parameters affect the intensity of vibration in underground openings due to blasting in adjacent opencast mine viz. total explosive weight detonated in a round, maximum explosive weight per delay, propagating media, depth of cover, RMR of the roof rock, age of the underground openings etc. Although a few researchers have tried to study the impact of parameters stated above, the impact of initiation sequences on generation of vibration in underground openings due to opencast blasting has yet remained untouched. A study was planned to evaluate the impact of initiation sequences on the magnitude of vibration in underground openings due to blasting in opencast mine. Nine production blasts with top and bottom initiations were performed at Samleshwari opencast project in India and eighteen vibration data were monitored in the roof of Hingir Rampur underground colliery in both the initiation sequences. The result indicated that the vibration produced in the underground openings from bottom initiation was lower than that of top initiation.

Jan 1, 2003

It has been common practice for many years to predict and control underwater blasting effects on the basis of certain simplified theories related to the pressures generated by underwater detonations. Unfortunately, two of the most commonly applied concepts in many instances do not provide an accurate modeling of typical field conditions nor the potential for damage. One of these concepts is that the damage potential is related directly to the peak pressure generated by an underwater detonation, without regard to the time history of the pressure pulse. This belief has led to the widespread use of air bubble curtains to reduce peak pressures, without considering the effect that air curtains have on the time history of the pressure pulse. At times, this procedure can be unwise. The other concept is based on the premise that pressure pulses in solids (such as rock) will always be transmitted to nearby water bodies in agreement with the theories of the transmission of plane waves across normal (perpendicular) boundaries. In reality, such conditions are quite rare.

Jan 1, 1985

By Robert L. Brooks

This paper is intended for companies at all levels of the Explosive Industry and in particular, those that do not have a risk manager. It is strictly informational in nature and no reference is made, or intended towards any existing insurance company or agency.

Jan 1, 1993