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By Ruilin Yang

The vector sum peak particle velocity (PPV) of blast vibrations describes the blast vibration intensity more completely than the PPV of a single component waveform. It is more logical to use a vector sum PPV as a vibration limit than using a single component PPV. In 1980 the USBM recommended the frequency related peak particle velocity criterion. So far this method has been only applied to single component waveforms, but not to the vector sum PPV since there is no method available to associate a frequency to the vector sum PPV. The present paper describes a method to define a principal frequency associated with vector sum PPV. The method is based on the weighted average of the principal (zero-crossing) frequencies of the three tri-axial components at the time of the PPV.

Jan 1, 2015

By Joshua Hoffman, Rob Farnfield, Catherine Johnson, Braden Lusk, Morgan Lane

IMESAFR (IME Safety Analysis for Risk) is a quantitative risk assessment software tool developed by the Institute of Makers of Explosives (IME) and A-P-T Research, Inc. It is used for managing risk in the commercial explosives industry, the newest version of the software was completed in 2012. This paper discusses the use of this software package in conjunction with data collected for a television series on the reenactment of the ‘London Blitz’, a 57-day bombing of the City of London in 1940. In this reenactment, purpose built structures using period design and materials were constructed at a test facility in the North of England. Five devices ranging in size from 20 kg (44 lb) to 1100 kg (2400 lb) were detonated at varying distances from the structures; each blast was monitored by EPC-UK and the resulting structural damage was analyzed. Data recorded from the blasts included high-speed videos, photographs before and after each event and air overpressure readings. The same data was inputted into the IMESAFR software package to assess the risk imposed on the residents of London during this time. The appropriateness of this tool for evaluating structures built using historical practices is discussed. Data from the full scale tests is compared to effects predicted by IMESAFR. Further analysis of the risk recommendations produced by IMESAFR is compared to the actual damage assessed during the large scale tests.

Jan 1, 2014

By Piotr Mertuszka

Many years of research on more effective and safer explosives have led to the development of emulsion explosives. They are the second most commonly used group of explosives worldwide, primarily because they are good alternatives to ANFO or dynamites. Their key advantage in underground applications is the lower content of toxic fumes in the detonation products. Emulsions are also characterized by high detonation velocity, high water resistance, low critical diameter, and mechanical loading capacity. Several factors affect the behavior of emulsion explosives. These factors are related to both manufacturing and applied mining methods. The most important factors include the charge diameter, type of sensitizer, density, hydrostatic pressure, ambient and charge temperatures, as well as the time elapsed between the charging of the explosive into the blast hole and its detonation. The selection of the type of explosive is based on the analysis of a number of parameters, including the density, critical diameter, volume of the post-blast fumes, detonation pressure, velocity of detonation, and sensitivity to external energy sources. In most cases, the conditions under which explosives are used differ significantly from those defined in standards. Such conditions cover, among others, the temperature of the rock mass and surroundings, humidity, rock strength parameters and the diameter of the blast holes. Consequently, the parameters of the explosives provided by the manufacturers may not correlate with those specified in-situ. Thus, within the framework of this study, the effects of the selected technological parameters on the detonation velocity of bulk emulsion explosives are presented. The analysis focused primarily on the factors directly influenced by the mine blasting services. The detonation velocity measured using the continuous wire resistance technique was used as the evaluation criterion. For this purpose, several underground in-situ tests were conducted, including the impact of the blast hole diameter, density, initiation method, sleeping time, and temperature on the detonation velocity. The results of in-situ tests have shown that the detonation velocity of bulk emulsion explosives depends strongly on the above factors, which may directly affect the effectiveness of blasting operations.

Jan 26, 2026

By Vitor Barcelos, Eduardo Elói, Gabriella Vaz, Davi Oliveira, Leandro Silveira

Following a routine production blast at Vale S.A.'s Itabira Mine in the Quadrilátero Ferrífero region of Minas Gerais, Brazil, nearby residents registered complaints about blast-induced vibrations. Analysis of the blast footage revealed that multiple blastholes were detonated simultaneously, resulting in a higher-than-expected charge per delay, ground vibration and cratering even though the electronic delay timing was configured correctly. Subsequent blasts within the mine's soft schist region confirmed the occurrence of sympathetic detonation. Mitigating or eliminating this phenomenon is critical for the mine's operation. Two dynamic pressure tests were conducted using carbon resistors together with typical VOD monitor maintaining the standard booster, electronic detonator, and a blend of 70% emulsion with 30% ammonium nitrate explosive. The tests involved increasing the distance between the central hole (detonated first) and the four surrounding holes in a five-hole sequence. Unfortunately, sympathetic detonation occurred in all these tests. To address this issue, a new explosive with a lower density and detonation velocity was tested. This approach proved promising, as no sympathetic detonation occurred. By leveraging the data obtained from this study, engineers can now identify situations at risk of sympathetic detonation and implement preventive measures, such as selecting the appropriate explosive and recommending safe minimum burden and spacing settings as well as confinement level for each blast while maintaining the desired level of rock fragmentation.

Jan 21, 2025

By Jianping Li, Ernesto Villaescusa, Kelly Fleetwood

During blasting, stress waves propagate through a rock mass, inducing stress and strain changes. This applied deformation affects intact rock, existing discontinuities, mine excavations, and engineered structures in the proximity of the blast. Traditionally in blasting, stress waves are quantified in terms of peak particle velocity (PPV) or peak particle acceleration (PPA), based on the method of measurement and the specified allowable tolerances. During analysis, the peak particle motion is coupled with an explosive source through various scaling laws to develop rock-specific attenuation relationships. Some studies have expanded this practice to the development of damage threshold values based on measured or predicted peak particle velocities. PPV-related thresholds are generally based on empirical models, where observation of overbreak, cracking, or fall-off are used to quantify damage. This method is often paired with the application of elastic plane wave equations to calculate the blast induced strain or the PPV threshold for tensile rock failure. Other factors that must be viewed critically in such models are the methods used to collect and analyse blast vibration data and the application of inappropriate vibration attenuation relationships.

Jan 1, 2009

By Travis Davidsavor, David Provost

A segment of high-pressure steel petroleum pipeline needed to be replaced on a hillside and beneath a waterway within an existing right-of-way containing multiple petroleum pipelines. The pipeline replacement required excavation of sedimentary rock to allow placement of the new pipe. As a result of an existing right-of-way limitation, steep slopes, and hard rock, blasting would be required as close as 7.8 meters (25 feet) from two operating pipelines. Existing pipeline company standards would have effectively precluded the construction of the replacement pipe by blasting rock. To facilitate the required construction and evaluate actual pipe stress during blasting to ensure pipeline integrity, a comprehensive evaluation methodology was developed by a team of pipeline, mechanical, geotechnical, instrumentation, and blasting engineers. A total of 60 strain gages were affixed to the steel pipe and seismographs were buried at the surface near the blasting area. Test blasting allowed pipe stresses with corresponding ground motion to be monitored. A conservative analysis approach evaluated individual peak strains and revealed that only small pipeline strains, and therefore stresses, were induced in the pipeline as a result of blasting. This evaluation allowed specific procedures to be developed to inform the blasting operation of maximum explosive loading and minimum charge distances. Additionally, this effort provided the pipeline operator with appropriate pipeline operating pressures during blasting activities to limit total stresses in the pipeline to be below allowable stresses imposed by code, regulators, and company operational limitations. Recommendations were developed to measure the blast generated ground vibrations with seismographs buried at the depth of the pipe, near the pipe, and limit the ground vibrations from blasting to 150 mm/s (6 in/s). If ground vibration intensities of 120 mm/s (4 in/s) or more were observed, additional engineering review is recommended. Finally, all blasting would be suspended and all activities reviewed at peak ground vibration intensities of 230 mm/s (9 in/s). The evaluation effort resulted in effective and efficient construction of the pipeline replacement and allowed the pipeline operator to better understand blasting induced stresses on their assets.

By Jeff Hiedeman, Clint Sestrich, Christopher Hyle

Westslope Cutthroat trout have declined in distribution and abundance across their range and currently occupy about 59% of their historic habitat. Due to hybridization with non-native species such as rainbow trout, genetically pure populations persist in only 10% of that range. A westslope cutthroat trout population with relatively high genetic purity (97%) and conservation importance persists in less than two linear stream miles in the headwaters of the South Fork Madison River in southwest Montana. The relative purity of this population has been maintained through the presence of a downstream intermittent reach. However, spring flows fill the intermittent reach, creating a connection between occupied westslope cutthroat trout habitat in the headwaters and the habitat of competing trout species downstream.

Jan 1, 2011

By Stewart A. Silling, D. Lynn Gordon, C. Mick Lownds, Dale S. Preece, Ali Bhuiyan, Patrick R. Bowden

Blast heave modeling and prediction utilizing the new discrete element model, GEM, that treats rock as elements with alternating arcs and line. Explosive loading of GEM elements is accomplished by utilizing the Noble-Abel equation of state to track the gas pressure from detonation through expansion to atmospheric pressure.

Feb 1, 2020

By Travis A. Davidsavor, David A. Provost

A segment of high-pressure steel petroleum pipeline needed to be replaced on a hillside and beneath a waterway within an existing right-of-way containing multiple petroleum pipelines. The pipeline replacement required excavation of sedimentary rock to allow placement of the new pipe. As a result of an existing right-of-way limitation, steep slopes, and hard rock, blasting would be required as close as 7.8 meters (25 feet) from two operating pipelines.

Feb 1, 2020

By Raúl Carretero de la Hoz, Leonardo Soares Chaves, João Paulo Soares Toneli, Francisco Felipe da Silva Dantas, Marcos Peres Lopes, Marcus Vinicius da Silva Gonçalves

The mining activity results in environmental impact and thus requires the adoption of techniques to minimize its effects. The rock blasting process is required to break up and move the rock enabling the haulage of the material, however, it might also cause undesirable effects such as flyrock, overbreak, excessive ground vibration or air-blast at the neighboring communities and damage to civil or geological structures located nearby. The Serra Sul mine, commonly referred to as S11D project, has obligations to preserve two natural tropical montane lakes and several maximum relevance natural cavities whose legal preservation radius represents constraints to the mine development and operation. Controlling measures are undertaken to ensure preservation of the cavities, especially during rock blasting stage, with limitations of the maximum instantaneous charge (MIC) and ground vibration control. The demand for high productivity and the large areas with hundreds of blastholes to charge are challenging factors to the charge control. This work presents the development and field application of a map for limiting explosive charges in the rock blasting process at the Serra Sul mine, used for the definition of maximum charges according to the blast location, ensuring the preservation and compliance with the defined ground vibration limits for each cavity. The map is applied at the mine for every blast and when there is a charge constraint, the map helps to define the areas with different charging profiles in the field contributing to higher charging productivity.

Jan 21, 2025

By P. Couceiro, J. Navarro

A new methodology to perform selective blast designs by adapting the explosive energy, hole by hole (or in the hole), to the rock properties as a combination of their strength properties through the X-Rock model has been developed based on drill-monitoring data from both autonomous and manual rotary drilling modes. For that, a thorough normalization process has been developed to minimize external influences in the data induced by the different rig system and the operator interventions during manual drilling operation. Principal component analysis has been used to combine drill monitoring information. Data from 48,385 blastholes, comprised in 102 production blasts at 7 different levels in one expansion of the mine have been used for the analysis. The methodology, called X-Energy, combines the X-Rock model outputs with actual blast design parameters (drill pattern, stemming and borehole length, explosive mass/density and others) and a constant variable obtained from a machine learning algorithm, to estimate size distribution and percentage of fines and coarse material, hole by hole, by combining and recalibrating the Kuznetsov (Cunningham, 1987) based equation. From it, a new shovel-independent diggability model has been developed as combination of the P80 size, the rock properties (from the X-Rock) and a constant variable obtained from a machine learning algorithm. The X-Energy application presented in this study have been implemented in Minera Escondida Limitada (MEL), to design and operate production blasts with the goal of varying the explosive density to the rock properties to obtain a more uniform size distribution and digging rates, hole by hole, based on a target size and rate, and improving slope care, preventing active faults to fail. The methodology has been applied and validated in 17 production blast (8,277 blasthole), unlocking an average of 12.8% reduction in explosives costs (explosive consumption), by combining a pattern expansion strategy and a better distribution of the explosive density within the blast. The results demonstrate how a better distribution of the explosive energy by varying its density in the hole according to the rock and blast geometry variables can reduce powder factor (explosive consumption) while improving or maintaining blasting and digging results.

Jan 1, 2024

By Tyler Acorn, Paul Worsey, Nathan Rouse

The effect of the hole diameter on vibration attenuation has not been incorporated in most vibration models in the blasting industry. In current vibration models, the charge weight and the distance from the blast are the two primary variables that are addressed. Charge weight is a function of explosive density, charge length, and charge diameter. This geometry-weight can complicate the isolation of the charge diameter variable.

Jan 1, 2013

By O. Rielo, A. Pascoal, P. Katsabanis

The dynamic parameters of two different granites have been obtained using Hopkinson bar experiments. One series of experiments were conducted using a Hopkinson pressure bar apparatus with an explosive source to provide the compressional wave. This wave would travel along the granite bar and would be reflected at the free end. Strains were obtained along the bar to examine the process. Using relatively long bars of rock, approximately 300mm long and 18mm in diameter, the separation of the compressive and the reflected tensile pulses was possible. If the net tension exceeds the strength of the material, spalling is witnessed. By properly selecting attenuation materials and explosive sources, single spalls were created, making results easier to interpret. Numerical modelling enabled the calculation of the propagation of the stress wave along the bar and its reflection at the free end. Knowing the location of the spalls, critical stress levels for rock failure under tension were obtained. Dynamic tensile strengths were also obtained, at different strain rates, using a Split Hopkinson Bar Apparatus. The results provide a measure of the increase of the dynamic strength at high strain rates, relevant to blasting applications. They are useful for the calibration of blasting models and the characterization of rocks for blast modelling, but also provide answers to the basic question of what is the rock strength for blasting applications.

Jan 1, 2011

Controlled Blasting, Inc. (CBI) located in Norcross, Georgia recently teamed with the Dekalb county fire marshals office to stage a mock disaster to test new trainees of Community Emergency Response Team (CERT). It as an interesting example in which industry can help out the community and government through the use of explosives.

Jan 1, 2010

By Ethan Steward, Kyle Perry

Blast resistant structural design continues to be a research area of major concern for governments around the world due to explosive threats from both state and non-state actors. Glass and aluminum curtain wall systems are commonly used to clad the exterior of government and commercial structures, allowing light into the building, regulating the interior environment, and providing an aesthetically pleasing exterior. These systems are likely to fail when exposed to sudden, high-pressure events such as the purposeful or accidental detonation of explosives. Engineers have designed blast resistant curtain walls and structural elements to reduce the likelihood and severity of failure, but the design tools and testing mechanisms commonly used in the process may not accurately model or simulate actual blast conditions at all ranges. In blast resistant structural design, the origin of a shock wave is typically assumed to be in the far-field, creating a wave that is nearly planar and parallel to at least one face of the target. Shock is applied evenly and immediately across the entire impacted surface. However, the source of real-life blasts is often very close to the target structure, and the assumption of far-field planar shock does not always apply. Mid-field blasts exhibit qualities different from those assumed about far-field shocks, specifically a hemispherical shock that produces different peak pressures, impulse curves, oblique reflections, and Mach stems across a target. This paper will examine mid-field shock effects from scaled distances of 2.5 to 4 13 (6.3 to 10.1 13) on a tall, scaled target by measuring reflected and incident pressure, impulse, and shock velocity across the target. Results will be compared to theoretical blast parameter equations and empirical data used by the industry. Possible effects of mid-field blasts on structures and further research ideas will be suggested.

Jan 21, 2025

By Piet Halliday, Ellina Kharatyan

Conventionally, emulsion matrices (unsensitized) need to be sensitized to become detonable explosives. This is done either chemically or mechanically. Both methods have their advantages and disadvantages. Mechanical sensitization involves the addition of microballoons (plastic or glass) to the emulsion matrix, in order to create hot spots during detonation. This is usually done at the manufacturing site and poses a safety risk in terms of the storage, transportation and handling of a 1.1 type explosive. Many countries throughout the world make use of chemical sensitization as opposed to mechanical sensitization as this allows for the storage, handling and transportation of two 5.1 type products rather than the 1.1 type explosive. Chemical sensitization involves the addition of a small amount of a chemical that reacts with a component of the emulsion matrix causing the formation of gas bubbles that act as hot spots during detonation. The disadvantage of this is the lack of accurate density control (due to various factors affecting the reaction) and the lack of comprehensive understanding of the operators of the reaction. This can easily result in poor blast performance. Due to these disadvantages a pumpable, non-detonable (5.1 type) mechanical sensitizer was researched and developed. This product allows for pumping at a 50:50 volume ratio with the emulsion matrix, when loading into blast holes. The significance of this is that a 1.1 type explosive is formed in the blast hole. As such, the security and logistical issues of the transportation and storage of the 1.1 type explosive are eliminated. Another advantage is accurate density control of the final product, specifically in small diameter long hole applications. A cost effective, unique mini pumping system has been developed for the loading of this product. Moreover, this system can easily be used for secondary blasting applications and the on-site packaging of cartridged explosive products.

Jan 1, 2015

By Tom C. Palangio

Commercially available online particle size analyzers (OPSA) are in their third decade of development (Palangio, T.C., 1985), (Franklin, J. A., Maerz, N.H., 1987), (Maerz, N.H., Franklin, J.A., and Coursen, D.L., 1987). The installed base of operating analyzer numbers is in the hundreds. This paper takes a look at five critically important relationships that users have discovered through the use of OPSA systems. The two key attributes of these systems are: 1) consistency and, 2) historical context compared with traditional practices.

Jan 1, 2016

By Guillermo Lazcano Ríos, Jorge Parvez Aguirre, Alejandro G. Díaz Berríos, Felipe Rodriguez Alveal

Codelco's Chuquicamata Underground Division (DCHS) faces issues due to collapses in its subsidence streets, which hinders the advancement of the subsidence front and leads to the loss of areas and reserves. To address these issues, DCHS and Orica have developed a new excavation methodology based on pre-loading explosives in high drawbell. This methodology involves creating a high drawbell extending from the floor of the production level to the ceiling of the subsidence level, divided into two phases: upper and lower. A resin stemming is used to separate these phases. The excavation strategy adjusts to variables such as reception volume, fluffing, and excavation geometry, involving vertical pre-loading of the explosive and the use of a separating element between the phases. The test aims to validate the new excavation methodology and the retaining element in the rock mass, evaluating aspects such as drawbell geometry, impact on the rock mass, damage to the retaining element, and fragmentation. Wireless electronic detonators are used in the upper phase to improve safety by eliminating the need for physical connections, while traditional electronic detonators are employed in the lower phase. Low-density bulk emulsion is applied to minimize the impact on the Crown pillar and extraction point, and higher-density explosives are used above the subsidence level to ensure good caving. Results showed that the blast achieved 86% conformity with the theoretical design. Resin stemming allowed for 100% effective detonation in the upper columns, and the fragmentation obtained was 5.44 inches, which was less than expected. No damage to the Crown pillar was observed, and the explosive quality met standards. This technique has proven to be effective and viable, suggesting the possibility of eliminating the subsidence level in future levels, resulting in savings, and providing greater stability to the rock mass.

Jan 21, 2025

By María Rocha, Benjamín Cebrián, Roberto Laredo

"Ring blasting designs have to achieve different goals in order to become efficient whether is done in up hole or downhole fashion. Ore recovery/dilution control, fragmentation and drift integrity all have to be taken into account when selecting parameters such as burden, spacing, linear explosive density and stemming. Blast energy simulation allows identifying contours of rock breakage and fragmentation, thuschoosing a combination of spacing at the end of holes and appropriate burden. Also, simulations are keyto concentrate energy levels on the mid part of the ring while making sure there is not too high of energy concentration around the drift, which integrity is needed for a safe ore mucking."

Jan 1, 2017

By Peter Dare-Bryan, Will Hunt, Lee Julian

It is well-known that blasting has an economic effect on grade control activities. However, until recently, methods did not exist for measuring the grade control value change caused by the blast. Rules of thumb were the best method to minimize ore loss and dilution, as simulation has been traditionally constrained by time and computer power. Even with these rules followed, an extensive study performed on over 150 blasts showed that the value change caused by the blasts followed a normal distribution – some blasts created value, and some blasts destroyed value. The question naturally asked was “How can we ensure the blast designs are optimized to create value?” Recent advancements in computer power have enabled real-time blasting simulations that create post-blast grade control models before the blast is fired. Understanding what will happen before it happens allows blasters and grade control personnel to iterate designs, searching for the highest value achievable.

Feb 6, 2023