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By J. D. Aubertin

Rock blasting is a complex engineering process that requires in-depth knowledge of operations and geomechanical conditions. Acknowledged design precepts are based on cratering behavior associated with stiff hard rock masses. Other cratering mechanisms may however arise under certain geomechanical conditions such as extremely fractured rock masses, or with soft rocks such as rock salt and potash. The burden dimension also plays an important role in the prevalent cratering mechanisms of a given blasting condition. The present article investigates the variability of cratering profiles and geometrical trends based on characteristic geomechanical differentiation and considering the influence of burden. The differences in observable mechanisms are examined through small and large-scale single hole blast (SHB) tests. SHB tests involve a series of individual shots blasted parallel or sub-parallel to an open face. The burden dimension is varied to obtain burden dependent characteristic trends. The breakout shape is represented by a crater model in the form of a power law equation capable of describing prismatic, concave and convex cratering. The formulation comprises two reference index parameters that can describe the geometrical and geomechanical conditions. SHB test campaigns conducted in rock salt, limestone, massive amphibolite, pinolite, and grout blocks are compiled in quantitative manner to demonstrate the influence of geomechanics on cratering profiles. The observed trends are corroborated through numerical modelling carried on Finite Element Model (FEM) LS Dyna to investigate the prevalence of specific cratering mechanisms. A series of SHB tests at large and small burden values are also used to showcase the influence of geometry on the prevalent cratering mechanism and the resulting crater

Jan 1, 2024

By Andrea Brickey, Ethan Marcoux

The South Dakota School of Mines and Technology (SD Mines), located in Rapid City, South Dakota, is one of only a few universities in the United States that offer a Bachelor of Science in Mining Engineering. The Department of Mining Engineering and Management (MEM) at SD Mines teaches courses that introduce students to concepts related to mining, including a course covering explosives engineering. Students are taught the basics of explosives theory and application in the mining and construction industry through a series of lectures and assignments. With limited field experience, many students find some topics difficult; these include: flyrock, ground vibration, timing, and others. Some US mining schools have an experimental mine in which they can simulate field conditions and conduct hands-on training, but not all universities have such facilities. For those without, teaching certain concepts can be more challenging in a pure classroom environment. To counteract the lack of an experimental mine, the mining department at SD Mines implemented Paradigm (Version 18.4.4984.0; McKenzie, 2017) a computerbased blast modeling software to improve the learning environment.

Jan 1, 2019

By Frank Lucca

This paper includes research and investigation into blast design and blast optimization for vibration control in municipal and tight blasting situations, where specifications were extremely stringent. The paper is written for the field blaster to understand and develop blast plans based on field conditions. The paper includes blast design considerations, utilizing seismograph arrays to check and predict vibration results, and problems encountered in vibration monitoring in extremely tight situations (0-20 feet). Blast vibration frequency, acceleration, peak particle velocities, and relative displacement are discussed with effects in the near and far fields and blast designs utilized to stay under limits. The paper also discusses using the latest in technology for blast design to control vibration. Equipment includes 2D and 3D laser profiling systems, digital video, fragmentation analysis, seismograph arrays, and borehole tracking devices. Other topics are discussed such as public relations, working with regulatory personnel, unions, and other project consultants, and the problems associated with municipal blasting situations, such as, flyrock and proximity of other personnel and equipment on the project.

Jan 1, 2004

By David Siskind, Mark Stagg

Vibrations from Dade County (Miami area) quarry blasting and structure responses were measured at 11 locations between February and April, 2000, and 10 homes were inspected to analyze the characteristics of their cracking and other damages. These results were combined with information collected by the County and other studies done in south Florida for a blasting impact assessment specific to this area. In addition over 40 quarry blasts in the nine-week monitoring period, about 800 measurements were available from previous monitoring in Dade and neighboring Broward counties. An overall worst-case analyses based on the highest individual amplitudes suggested that vibrations in some areas could have been as high as 0.35 in/s. While amplitudes in the study period were below this value, they were found to be relatively high for the distances and charge sizes. Attenuation with distance is less in Dade County than found elsewhere with quarries having to use scaled distances several times higher than similar sites in the north. Consequently, the vibrations are perceptible at very large distances.

Jan 1, 2001

By D. Goodings, W. L. Fourney, Bonenberger, R., Uli Leiste

The Dynamics Effects Laboratory at the University of Maryland conducted a series of very small scale tests to measure the impulse delivered to a plate by the detonation of an explosive charge which was buried in saturated sand. These tests were conducted to support a full scale tests series being supported by the Navy (NSWC Indian Head Division) to learn more about loads applied to structures by explosive detonation. For each of the tests being predicted, a series of three tests were conducted at Maryland, one with a 0.203 gm charge, one with a .609 gm charge, and one with a 3.3 gm charge. A high speed digital camera (500 frames per second) was used to record the displacement of the plate as a function of time. From this the initial velocity of the plate was determined and then the impulse delivered to the plate by the explosive. A best fit line through the data was determined for the three model tests conducted and this equation was used to extrapolate the predicted impulse for the full scale tests.

Jan 1, 2005

By Robert Hopler

BH Note: This price list stresses the point that the number six strength cap should be used with all high explosives. It’s interesting that duPont chose to continue to supply the lesser strength caps – but lowered the price of the #5 or #6 to be closer to that of the #4 and #3. There were imports of the lower strength caps at the time that had to be competed against, hence the price reductions. Another interesting point on this price list is the noting on the “Red Cross Explosives” page that these explosives reduce the danger incurred during the operation of thawing. As noted many times in these articles, this problem was not to be solved for about another 16 years or so.

Jan 1, 2011

By Robert Hopler

HUDSON MAXIM A Noted Inventor of High Explosives ALTHOUGH the subject of the present sketch has been a tireless worker in many fields of activity, his name is best known in connection with his work in the development of high explosives and their application to modern ordnance

Jan 1, 2012

By Robert Hopler

True there is a certain proportion of nitro-glycerin in dynamite cartridges, but the dangerous explosive is scientifically compounded with wood pulp and some other ingredients in such a way that it can be absolutely depended upon not to explode accidentally if our simple and plain instructions for its use are complied with.

Jan 1, 2012

By Tom Snyder, John Brulia

"The U. S. commercial explosives industry annually transports thousands of tons of hazardous materials (HM) in the form of explosives, oxidizers, and combustible liquids by highway in truck-tractor/trailer combinations and straight trucks, including pickups. Managing risk during transportation is every commercial explosives industry motor carrier’s number one job."

Jan 1, 2014

By Doss Brittain

The term ground breaking is taken to include the process of so loosening the ground as to enable it to be readily loaded into buckets or cars and hoisted from the shaft or drift. In the Joplin district are encountered two varieties of ground, the hard and the soft. Hard ground consists of massively bedded rock requiring heavy blasting to loosen it. Such ground is to be found throughout the district in the same localities as the soft ground but more extensively, even to the exclusion of the appearance of soft ground in the sheet formation in the vicinity of Webb City. The Yellow Dog Mine at Webb City and the Grace mine on the Granby land at Joplin furnish well known examples of hardground mining which has become the most extensive in the district.

Jan 1, 2008

By Tacio Ferreira

How state-of-the-art software, data analysis and communication applied to drilling and blasting techniques have have allowed quarries in the Midwest of the United States to improve results downstream

Feb 1, 2020

By Z X. Zhang

In sublevel caving mines, eyebrow break usually gives rise to lower ore recovery and worse safety in the field. Eyebrow break is caused mainly by two tensile stress waves: one from the front surface of a blasting ring, and the other from the roof of the drift. In order to reduce the two waves and finally to reduce eyebrow break at Malmberget mine, we employed two methods: (1) cartridge charge, and (2) double-primers in each blasthole. The two methods were tested in one ore body called ViRi. A total of 10 rings with the cartridge charge and 25 rings with the double-primers were blasted. At the same time a total of 34 ordinary rings were blasted in the same ore body. The result shows that the eyebrow break is 3.0 m for the ordinary rings, 2.3 m for the cartridge charge rings, and 2.1 m for the double-primer rings, respectively. In addition, the ore recovery for the double-primer rings is increased by 3% on the level of ViRi930, compared with that for the ordinary rings.

Jan 1, 2011

By Robert Hopler

Of the common causes of the larger mine accidents, such as falls of roof and coal, gas and dust explosions, mine fires, and the misuse of explosives, all of which are often closely related, each must be studied and fought in a manner peculiar to itself. The last mentioned, the misuse of black powder and other explosives, is sometimes considered the least important of these causes of mine accidents; but its importance is much greater than the statistics indicate, for the reason that the misuse of explosives is the true cause of many of the fatal mine fires, gas or dust explosions, and falls of roof that are credited to other causes.

Jan 1, 2012

By William Hissem

The topics in the title line of this article are desirable and applicable to entire industries that exist outside the realm of the ISEE’s readership. But the issues I will discuss herein are specific to those who drill, blast, and excavate rock as part of their business. Civil and site construction projects, mines, and quarries specifically comprise the group who will benefit from this discussion.

Jan 1, 2014

By Wilfrid Comeau

Vibrograms, which last significantly longer than the actual blast (say 10 to 15 cycles or more), may be signalling an elastic response, which is not uniquely blast related. For example, geophones mounted on a part of a structure, which can elastically resonate at a frequency included in the seismogram, may not show the structure’s real reaction to the blast. This resonance usually amplifies the ground vibration. This contribution examines one particular case where blasting excited and amplified a resonant ground response, and the method used to significantly reduce or eliminate this undesirable condition.

Jan 1, 2007

By Andy Hudson, Stuart Brashear, David Lilly

Because of greatly increased timing accuracy, electronic detonator systems are a well-known and widely accepted major tool to control and reduce ground vibration. At a Southeastern quarry the authors found that the use of electronic detonators improved the reliability of the well known cubed root scaled distance equation for determining air blast. In addition, the authors noticed significant correlations between selected major peak particle velocity frequencies and air blast magnitudes. The major peak particle velocity frequency alone is a close approximation to air blast magnitudes. This relationship is not as significant or not always evident when standard pyrotechnic initiation systems are used.

Jan 1, 2009

By Scott G. Giltner, Paul N. Worsey

During the short duration of an explosive blast, many events occur which are too quick to be detected or observed in detail with the naked eye or by normal photographic techniques. Through the use of "hightech", high speed video, many of these events can be observed, instantly played back and recorded for later use. The use of a Spin Physics SP 2000 Motion Analysis System at a blast casting operation is presented. The variable range of recording speeds offered by the SP 2000 allowed it to be used for examination of different areas of blasts. At its maximum full frame rate of 2000 frames per second the SP 2000 can easily pick up the flame front as it travels down a nonel tube and the flash from the surface delays as they fire. The system was used for a variety of tasks including, but not limited to,the determination of delay accuracy to within 0.5 ms, the velocity and trajectory of the faces during blasts, and pinpointing geological problem areas. The effectiveness of the system as used on site is discussed along with detailed method of set up, recording, playback and data processing. Other details including site specific environmental and lighting problems are also covered.

Jan 1, 1986

By Virgil J. Stachura, Calvin L. Cumerlato

The U. S. Bureau of Mines is conducting research on blasting methods that reduce highwall overbreak and the associated rockfall hazards. This paper presents the results of tests using a low-density water gel to improve the quality of air-decked presplit blasts at a surface coal mine in New Mexico. The explosive's specific gravity averaged 0.50 and was bulk loaded using a modified truck which injected the gassing agent. Reductions in overbreak and resulting rockfall were achieved in comparison to a highwall presplit with ANFO. The test sections used 15° angled blast holes and resulted in 1,119 m (3,672 ft) of air deck presplit highwall using a low-density water gel which was then compared to 894 m (2,934 ft) of highwall shot with an ANFO air decked presplit design. The total quantity of explosives per hole ranged from 68 to 113 kg (150 to 250 lbs) and the 27 cm (10-5/8in) holes were 19- to 33-m (62- to 108-ft) deep on 5.5 m (18-ft) centers. Periodic visual examination and photographic surveys of the highwall test areas were used to document the amount of rockfall. In addition, laser profiles of selected sections were conducted to further delineate the damage and highwall contour differences.

Jan 1, 1995

By L. Russell Payne

The use of shock tube in the blasting industry is relatively well characterized and understood within the realms to which it is used. Non-conventional uses of shock tube within the EOD and the Aerospace Industry however has not been as widely researched and published. Characteristics of shock tube such as its reliability, simplicity and its non-electric nature make it ideal for functioning or driving mechanical mechanisms, detonators, and timing devices. Outlined in the text are the performance characteristics of shock tube in an array of atmospheric environments including pressures ranging from ambient to 100,000 ft equivalent atmosphere. In addition the useful exit work energy or impulse of the shock tube for driving these various EOD and Aerospace mechanisms is published as a function of tube lengths and atmospheric pressures. Of particular interest to these devices is the required length of shock tube needed to produce the steady state detonation energies and the accompanying properties of the shock tube at these lengths. Various sources publish an arbitrary run distance for steady state detonation and output some where between 20 cm and 1.0 meter. Statistical and experimental evidence with in the text show these numbers to be low and provides an updated reference for shock tubes usage in nonconventional situations.

Jan 1, 2008

By Tristan Worsey, Jhon Silva

The paper discusses a limestone quarry case study that looks at change in fragmentation due to using different charge sequences when using the regular rhythmic timing method.

Feb 1, 2020