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By AK Chakraborty, AK Raina

Burden of drill hole is third most sensitive parameter effecting the ground vibration in blasting apart from maximum charge per delay and distance. Various types of burdens can be seen in practical bench blasting situations. Burden can be expressed as drilled burden and initiation burden. Drill holes may have various front row burdens (toe burden), which may be different from the designed burden. In order to ascertain the impact of front row burden as well as the initiation burden on intensity of ground vibration and air overpressure experiments were conducted in sandstone overburden benches of an opencast coal mine and limestone quarry. Blast trials were carried out in cognisance of both drill and initiation burden while keeping all other parameters constant. Effect of front row burden was also extensively studied by keeping almost all other parameters constant. The results of the study reveal that there is substantial influence of front row burden on the vibration and air overpressure. The statistical analysis of vibration and air overpressure data with drilled burden and initiation burden gives significant evidence that the level of peak particle velocity of vibration (Vmax)) is reduced by reducing effective burden with modification of initiation. Data analysis carried out for air overpressure versus initiation burden shows that reducing effective burden with modification of initiation results in increasing the level of P. The study reveals a qualitative assessment of the influence of burden on the blast induced vibration and air overpressure. The study also recommends to modify the initiation pattern to reduce the effective burden in order to reduce the vibration, without disturbing the fragmentation.

Jan 1, 2004

By Lazar Kricak, Zoran Teodorovis, Dragan Bogunovic

Scattering of delay interval around nominal value is an important issue in blasting practice. The scatter interval, as becomes wider, increases a probability of time delay overlapping adjacent blastholes. An excessive flyrock, ground vibrations, air blast and poor fragmentation are the symptoms for scattering related problems. Utilization of the short delays in the blastholes and longer delays on the surface are recommended solution to overcome mentioned problems. In contrast to global trends manifested through the application of electronic detonators and non-electric shock tube systems, revitalization of inexpensive electric detonators in combination with an accurate initiation system may be an acceptable solution. An extensive work was carried out at the Blasting Center Laboratory at the College of Mining and Geology, University of Belgrade, to develop a precise initiation system. As a result, Sequential Blasting Initiation System – Radio Frequency (SBIS-RF) was developed. It is expected that this system will increase blasting productivity, and reduce negative environmental impacts and total blasting costs.

Jan 1, 2008

By Mauritz Kotze, Jason Furtney, Ewan Sellers, Sandy Etchells, Tom Szendrei

The development of a simple model for gas flow and burden movement has driven the need to improve our understanding of burden breakage mechanisms for single hole blasts and the interaction between multiple holes in solid and jointed rock masses. Conventional analytical understandings of the burden breakout using the elastic-tensile fracture model were studied and found to provide a breakout angle that is independent of burden in contradiction to experimental data. By considering rock fracture in terms of Mohr-Coulomb plasticity using analytical expressions from the field of cavity expansion analysis an improved relationship between breakout angle and burden is derived until the point of critical breakout at which the angle of breakout suddenly changes from between 90 degree and 100 degrees to zero. This suggests that the critical burden occurs at about 0.6 times the radial fracture zone calculated from the analytical solutions.

Jan 1, 2013

By Jonathan D. Aubertin

The unique nature of rock salt blasting is compared to traditional hard rock practices. Rock salt geomechanical nature is discussed in the context of rock blasting events. A cratering mechanism prevalent in soft rocks is presented and exemplified through a series of single hole blast tests performed in salt deposits.

Feb 1, 2020

By Dr. Bronwynne Victor, Quentin Steyl, D. Scott Scovira

Bulk emulsions and emulsion blends may be formulated with a single salt, dual salts, or multiple salts. Blasting professionals familiar with single salt ammonium nitrate emulsion products may be less acquainted with dual and multiple salt emulsion products that may include calcium nitrate, sodium nitrate, and urea in their formulations.

Feb 1, 2020

By Robert B. Hopler

"The story of packaged explosives begins with the use of black powder (also called gunpowder) in mining. Although discovered in the 13th century, it was not until 1627 that the first records of use in mining is recorded. It took until the early 1800's before its use began in underground coal. Althougha free-running, granular material, its recommended (and safest) manner of use was for the miner to pour it into ready-made or onsite formed paper bags prior to insertion into the borehole. This was absolutely necessary in horizontal or upward-slanting holes."

Jan 1, 1991

By Roger Favreau, Patrice Favreau

The article reviews the aspects which contribute to the quality of the results from a blast with explosives, namely a good floor, no large blocks, easy mucking, and explains the mechanisms of the blasting process which decide on the quality of these aspects for a given blast method, and how these mechanisms can be simulated from basic principles. It proposes that good fragmentation size distribution can also be important if the rock is going to a crusher, e. g. for the ore in a mine and for the rock excavated in a quarry.

Jan 1, 2012

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 A. S. Romphf, C. K. McKenzie

Recent full-scale field studies involving single-hole charges fired to free faces under a wide range of operating conditions have delivered precious insights into airblast characteristics and propagation. The field tests involved production blasthole diameters in the range 89 to 406 mm (3 ½ to 16 in), bench heights in the range 9 to 24 metres (30 to 79 ft), burden ratios (burden/hole diameter) in the range 14 to 51, stemming ratios (stem height/hole diameter) in the range 11 to 36, explosive types of ANFO, heavy ANFO and pumped emulsion, and both solid-column and double-decked charge configurations. Around 700 measurements of peak amplitude and wave shape were made in all directions (0 to 360 deg) from the free face, from 38 single-hole tests in nine North American operating quarry/mine environments. The most striking observations were the strong dependence on directionality of the wave propagation parameters and wave frequency, the consistency of wave shape which resembled the modified Heelan wavelet, and the occasional appearance of distinct, multiple pulses from single events, shown to be echoes/reflections from quarry faces. In-hole deck charging failed in this study to achieve expected peak overpressure reductions, with the peak overpressure levels in Pascals/psi/millibars being approximately 40% higher than the as-charged weights. Inter-deck delay times in excess of around 25 ms are required for effective reduction of peak overpressure levels from front-row holes. Simple linear-superposition models based on synthetic wavelets applied to large production blasts produce composite waveforms which capture the important features of the actual pressure-time history, and correlate well with measured waveforms.

Jan 26, 2026

By Dale Preece, Joergen Pilz, Zavis Zavodni

An overland conveyor was constructed at a surface coal mine to reduce the truck haul distance and make the operation more efficient. An important element in this system is a truck dump facility to transfer coal from truck to conveyor. Mechanically stabilized earth retaining walls were employed to accommodate the coal processing equipment, including the crusher, in this facility. These retaining walls are close enough to the pits being mined that blasting induced vibrations must be considered in analyses of the wall structural stability.

Jan 1, 2010

By Roger Favreau, Patrice Favreau

Without blasting there can be no roads, no hospitals, no factories, not even foundations for homes. Yet in 1960 the only way to design a blast was by trial/error. By comparison, bridges were already designed by calculations before being actually built. This was possible because equations based on the fundamental principles of science existed with which all the stresses in the bridge could be calculated. In 1960 no equations based on the fundamental principles of science existed with which the mechanisms that take place inside the rock mass during a blast could be calculated. Since then the main author made it the objective of his research to seek such equations, and to validate that they gave accurate answers by means of experiments in the field, experiments made in co-operation with mines, quarries and the explosives industry; results have been reported in some 90 publications.These equations now deal with essentially all aspects of a bench blast: the intensity of the shock wave and the fragmentation size distribution throughout the rock mass; the movement of all the fragments into the muck pile; the fly rock and vibrations from the blast; etc.; are presented examples of such equations. They are now assembled into a computer simulator called Blaspa accessible on the Web, with which one can design a blast just as a bridge is designed. An example is presented. The reason to design a blast by simulations rather than solely by trial/error is that if it leads to damage, it is only after the actual blast that the blast design is realized to cause damage. If however the blast design had been simulated before the blast, then the risk of damage is identified before the blast and is prevented by redesigning the blast. Examples of such situations are presented. The need to a void damage is very necessary because the public is becoming opposed to blasting. When a blast does cause damage, and people learn that the blast was designed solely by trial/error even though simulation was available and would have prevented damage, they become even more strongly against blasting; they may succeed in getting a quarry closed. Their objections to unchecked blasting are not unreasonable, especially as simulating a blast with Blaspa on the Web is a very simple procedure.

Jan 1, 2013

By D. Preece

The mining and oil industry employs techniques such as geologic mapping, core drilling and electromagnetic and potential field techniques to explore for new deposits. Since new discoveries of major near-surface ore bodies are becoming progressively rare and since traditional exploration methods are unable to resolve ore bodies deeper than about 500m, high-resolution seismic reflection techniques show great potential for exploration to much greater depths down to almost 3km.

Jan 1, 2011

By Anderson da Cunha Meireles, Pedro Garcia, Ernst Young, Leandro Coelho, Carlos Eduardo Soares Feliciano, Key Fonseca de Lima

Rock blasting is a crucial technique employed in mining construction and quarrying industries to fragment large rocks into smaller, more manageable pieces. However, it often generates ground vibrations that can pose significant challenges. This study explores the application of Conformal Prediction (CP) in the context of rock blasting to develop predictive models that estimate blasting-induced vibrations and quantify the associated uncertainties. Various machine learning models were integrated within the CP framework using MAPIE and CREPES libraries. The results demonstrated the effectiveness of CP in providing statistically reliable prediction intervals, making it particularly useful for applications where the stakes of underestimating uncertainty can be high.

Jan 21, 2025

By M. K. Ameen, R. El-Hacha

This paper presents the analytical results obtained from numerical simulation of reinforced concrete slabs strengthened with various FRP systems and subjected to blast loading. A three-dimensional finite element model using AUTODYN software was used to predict the overall behavior of the slabs. The numerical results were validated by comparing with experimental results from a program carried out to investigate the efficiency of different strengthening systems on the blast resistance improvement of small-scale reinforced concrete (RC) slabs. The experimental program consisted of testing nine RC slabs strengthened with three different externally bonded (EB) FRP systems attached at the bottom side of the slabs and one RC slab tested without strengthening for comparison purposes. The EB FRP strengthening systems investigated included two layers of Carbon Fiber Reinforced Polymer (CFRP) sheets, two layers of Glass Fiber Reinforced Polymer (GFRP) sheets, and one layer of Glass-Fiber Resin Polymer (GRP) sheet. Different epoxy resin, patching mortars and impregnating epoxy adhesives were used for the slab surface preparation and FRP system application of the strengthening layers. The aim was to evaluate the residual strength of the test specimens after exposure to blast loads. The blast loading parameters were evaluated for each test using AUTODYN simulation and compared with the computer program CONWEP. All specimens were subjected to same spherical TNT charge weight and stand-off distance with the respect to the slab top surface. Extensive comparison is made between the experimental results and the AUTODYN simulations for the control unstrengthened slab and the strengthened slabs including time history records of the bottom steel strain and mid-span acceleration and the peak dynamic deflection of the slabs.

Jan 1, 2010

By Claude Cunningham

Blasthole pressure is the starting point for many blast design calculations, but the way in which it is usually derived, from measured detonation velocity, indicates that more thought is needed as to its true meaning and implication. The general impression is given that the energy in the hole is defined by VoD, but rarely is this the case. VoD is defined by the energy released in the Detonation Driving Zone between the shock front and the Sonic (or 'CJ') surface, and for commercial explosives it is normal for reaction not to be complete within this zone. Reaction and energy delivery continues behind it, not reflected by VoD. Thus it would be more appropriate to use the theoretical VoD, not the measured VoD, to derive the starting pressure, since this would reflect the energy input of full reaction. In decoupled situations, the derivation of pressure at the blasthole wall using a polynomial decay concept is also of debatable value, and an alternative is offered.

Jan 1, 2006

By Brian Lewis, Reinhold Daykin Schnell

Blasting specifications and guidelines are very important aspects of detailed project specifications covering any scope of work (SOW) that involves explosives and blasting procedures. A lot of larger construction or tunneling projects require some degree of project specifications for the entire scope of work on such project, including blasting specifications. It is important that all blasting specifications effectively and accurately address all explosives and blasting concerns associated with the SOW for such project. This includes safety and security, required personnel and their associated responsibilities, procedures and applications involving explosives, blast design and planning, blast monitoring and reporting, quality assurance and quality control, and local, state, and federal regulations and limitations. With the of wide range of information required in blasting and overall project specifications along with the risks associated with work involving explosives, it is also important to ensure qualified personnel are involved in interpreting or compiling and approving any blasting specifications and guidelines. The purpose of the following paper is to explore and present the basic information, as summarized above, that should be included and considered in the creation of detailed blasting specifications and guidelines. Detailed information is presented in specific relation to a potential bid package that would be compiled for a construction or tunneling project requiring protective or high-profile blasting.

Feb 6, 2023

By Sarah Guzzelli, Enrigue Munaretti, Anneliese Botelho, Jair Koppe

Drill and Blast (D & B) is one of the main operations in the mining production cycle, which aims to fragment rock according to a pre-defined plan for proper loading, haulage and processing specifications. In this sense, data from a Brazilian iron ore mine was analyzed, given emphasis on blasthole length, subdrilling and stemming. The D & B report, including mining data such as number of blastholes, length, and diameter and stemming aspects, was analyzed in order to be able to compare these results with the blast design. The study showed significant differences between the designed blasting pattern and that one obtained by the operation. As a consequence, problems such as inadequate fragmentation, incorrect size distribution and loss of energy, were identified. For example, when stemming has a different length than it should have, noise and flyrock can occur, including inadequate fragmentation and vibration in both situations. Therefore, a comparison between the usual D & B procedures and recommended D & B design based on literature reveals the most important deviations and their consequences. The study intends to identify solutions for simple problems, improving D & B operations and safety practices.

Jan 1, 2014

By Anne Caroline Costacurta Polli, Jose Rojas Cáceres, Roberto Mahler de Morais, Thais Costa Silva

The technology and the knowledge about the behavior of explosives and detonation accessories allowed to create new products for different situations by the restrictions imposed by the market. In a Brazilian underground copper mine the restriction occurred in the use of high grammage Det Cord in the development heading blasts perimeter holes. Enaex Brazil has developed Densiex UG™ (Low-Density Bulk Emulsion), a water-resistant bulk gassing emulsion with a density ranging from 0.60 to 0.90 g/cm³ to replace the high grammage Det Cord in blasts. That product is pumped in the same Mobile Manufacturing Unit (MMU) as Enaex Brazil's standard underground (UG) bulk emulsion. This product has a Lower Velocity of Detonation (VOD), vibration, and detonation pressure, which contributes to a better finishing of the drift, lower impact in the support structures, and lower generation on unstable rocks in the perimeter of the drift. This case aims to summarize the results of the work on the application of the Low-Density Bulk Emulsion in perimeter holes in an underground development gallery at an underground copper mine in Brazil. During this work, 10 horizontal drift blasts were performed using the Low-Density Bulk Emulsion, which presented an average density of 0.64 g/cm³, increasing safety, a 25% reduction in overbreak, a 23% reduction in scaling time, elimination of rework, and a saving of $135,000 per year for this business partner that immediately implemented this new product in all blasts at this mine.

Jan 21, 2025

By Jose Pineda, Abraham Lindo

The Panama Metro System’s Network expansion involves excavating a launching shaft for a tunnel boring machine (TBM) to traverse beneath the Panama Canal. The blasting needed for this shaft construction poses significant challenges due to the presence of concrete walls encircling the excavation. These walls must remain intact throughout construction and the tunnel's future operation. This case study is focused on devising and implementing safe blasting techniques crucial for the shaft's construction, ensuring the preservation of surrounding concrete walls and project equipment. As the interest was potential damage to the concrete walls, an appropriate vibration threshold for this project was also required as an alternative to the traditional U.S. Bureau of Mining RI-8507 limit (USBM RI8507). Blast modeling software was employed to conduct a series of blasting simulations. Parameters like hole diameter, spacing, depth, explosive type, and initiation methods were varied to evaluate their potential effects on wall stability and damage risk. The simulations revealed that smaller diameter holes and reduced spacing between blast holes would effectively mitigate the risk of wall instability. Additionally, utilizing electronic delay detonators and carefully planning the blast hole detonation sequence proved critical in minimizing potential damage. Executing these blasts in the field presented unique challenges, including strict charge per delay thresholds and logistical constraints. Consequently, continuous adjustments to blasting parameters were made and comparative result analysis. Beyond providing a safe blasting strategy for the TBM launching shaft, this study offers invaluable insights into adapting blasting designs to align with environmental and structural safety standards. These findings hold great potential to shape guidelines for analogous sensitive construction projects. They underscore the importance of leveraging prior research as a reference point, engaging with project designers and local authorities, and continually conducting testing and adjustments to ensure project success.

Jan 21, 2025

By Brian Stump, Rong-Mao Zhou

A series of single-fired (simultaneously detonated) explosions were conducted in an Arizona copper mine. The explosions spanned yields from 1700 to 13600 lbs (773 to 6169 kg) and were all detonated in an approximate 100 m by 100 m area. In order to quantify the effect of the mine free-face, the individual explosions were also detonated under three different emplacement conditions including at the free-face of the mine under normal burden, twice normal burden and fully contained. The purposes of these experiments were to investigate: (1) Generation of in-mine and regional phases such as Pg, Pn, and Lg from mining explosions; (2) Quantification of the relationship between yield and seismic amplitudes; (3) Quantification of the effect of confinement; and (4) Similarities and differences between single-fired waveforms and those from delay-fired explosions. Instrumentation was deployed at near-source (100-700 m) and in mine (1-5km) distances. Empirical scaling relations for the different shots in this test series were developed in order to quantify the effects of yield and confinement.

Jan 1, 2006