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By Robert B. Hopler

The hazards which naturally prevail in underground coal mines, always severe and unpredictable due to the loosely-consolidated strata in which coal is frequently found, are increased by the commonly-occurring combination of coal dust, methane, and explosives. It was recognized by the mid-nineteenth century that coal dust was the basic factor contributing to disastrous explosions killing hundreds of miners, and that the ignition of methane gas was often the source of the coal dust explosions. It was apparent that preventing the ignition of methane was a critical part of avoiding these disasters, and it was also apparent that one cause of such ignitions was the firing of explosives. In addition, it was found that dust explosions were often initiated by blown-out shots of explosives in the absence of methane.

Jan 1, 1996

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 Ali Kahriman, Abdulkadir Karadogan, Umit Ozer, Mehmet Aksoy, Deniz Adiguzel

The environmental problems arising from ground vibration has been faced and discussed frequently in various industries such as quarry, mining, civil works, shaft, tunneling, pipe line and dam construction etc. where the blasting operations are unavoidable. In bench blast design, not only the technical and economical aspects, such as block size, uniformity and cost, but also the elimination of environmental problems resulting from ground vibration and air blast should be taken into consideration. The prediction of ground vibration components plays an important role in the minimization of the environmental complaints. This paper presents the results of ground vibration measurements carried out in the quarries located on the different sides of Çatalca district in Turkey. In order to predict peak particle velocity level for this district, ground vibration components were measured for shots during bench blasting at these quarries. In blasting operations; ANFO is commonly used as blasting agent at the quarries. The type of priming and firing differed from quarry to quarry. The parameters of scaled distance (charge quantity per delay and the distance between the source and the station) were recorded carefully and the ground vibration components were measured for all blast events by using different type vibration monitors. The absolute distances between shot points and monitor stations were determined by using GPS. The equation of square root scaled distance extensively used in the literature was taken into consideration for the prediction of peak particle velocity. In order to predict, and compare the influence grades to the neighboring buildings, and structures at the Çatalca district, the particle velocities and frequency values of all blast events are evaluated according to the United States Bureau of Mines (USBM) and German DIN 4150 Norms due to the lack of a national standard in Turkey. Then, the data pairs belonging to these quarries were gathered together to represent the district and were analyzed statistically. At the end of statistical evaluation of the data pairs, an empirical relation which gives average line at 95% confidence level and upper bound 95% prediction line with a reasonable correlation coefficient was established between peak particle velocity and scaled distance

Jan 1, 2007

By Daniel Scott

Mines have used explosives for economical fragmentation for many years. It can therefore be expected that the mining industry has thoroughly researched how to achieve the most efficient blast. However, there is still a large amount of iteration that must be undertaken before blasting at a mine site can be refined enough to allow for consecutively successful blast results. And then the geology changes. This paper will present an approach to blast design that considers production goals, geology, budget, and safety, and will contrast the proposed method with well established blasting theory.

Jan 1, 2012

By Johan Gjødvad, Catherine Aimone-Martin, Charles Dowding, Mathias Jern

A residential structure adjacent to a quarry in Ohio was instrumented to record structure motions, resulting wall strains and existing crack displacements in response to close-in blasting within 82 m (270 ft). The project is a cooperative effort among international experts representing the European Federation of Explosives Engineers (EFEE) and ISEE supported by more than 21 persons from eight different countries to compliment prior work performed at the Aitik Mine in northern Sweden. The focus of this study is to compare blast-induced vibration measurements relative to regulatory compliance limits as a percentage of allowable velocities among eight different countries for a one-story residential wood-frame structure with a brick-and-mortar exterior and full basement. Participating counties included Austria, France, Germany, Norway, Sweden, Switzerland, the United Kingdom (UK) and the United States (US). Geophones were placed on the foundation and in the ground in accordance with each country’s regulations to record peak velocities as a function of frequency or distance to blasting. This study extends the work performed at the Aitik Mine to include interior corner geophones to calculate global wall strains and micro-m (micro-in) displacement gauges mounted over an existing drywall crack to measure blast-induced dynamic crack responses and climatological influences on daily opening and closing of a crack. Structure responses were documented for 68 blasts conducted north of the structure from February through September 2023 of which 17 blasts were selected for detailed analyses. The highest in-ground PPVs recorded were 43 mm/s and 59 mm/s at the NE and SW corners, respectively. Measurements from these blasts plotted within each country’s limits provided a comparison of stringency among the counties. The percentage of compliance limits among counties ranged from an average of 114% for the US, UK, and Austria limits to the highest of 585% for Switzerland. Despite these high percentages of compliance for all countries, the global tensile strains induced by these blasts were at most only 12 μ-strains and occurred with the highest velocity blast that exceeded each county’s limit. This high percentage of compliance and low strain level demonstrates the restrictive nature of the regulations studied. Peak dynamic crack opening and closing during blasting averaged 20 -m (0.0008 in) while the 12-hour weather-induced crack displacement during the time period over which blasting occurred averaged 200 -m (0.008 in) and the largest 12-hr change in crack width was 356 -m. This low level of crack response validates the observation that the studied regulations have highly conservative limits for cracking potential of standard building materials.

Jan 21, 2025

By David La Rosa, Matthew Craft, Lee Julian

Rules of thumb are ubiquitous in blasting. Typically presented as ratios, they assist with the initial assumptions of blast design and provide guidance for best practice. Examples include the blast hole diameter as a function of bench height, and stemming length as a function of hole diameter. The most common rules of thumb were developed in mid-20th century and it is important for a blaster to know if the rules of thumb are still reliable.

Feb 6, 2023

By Ethan Steward, Robert Eades, Kyle Perry

Shock tubes, either gas or explosively driven, are often used for physical modeling of free field explosions or arena testing. The use of shock tubes often requires less setup time of subjects and smaller driving forces to create pressure versus time waveforms similar to that of arena testing. However, the effects of the shock tube cross sectional geometry on waveform properties is uncertain while free field explosion wave propagation and estimation is well studied.

Jan 1, 2018

By Joshua Hoffman, Philip Mulligan, Braden Lusk, Tristan Worsey

Blasters rely upon detonators to achieve the designed timing sequence to move material where it needs to go, minimize vibration, or optimize fragmentation. At times detonator inventory on seldom used delays may be slow moving. This can lead to detonators being used long after they were manufactured. This paper addresses the potential shelf life concern as it relates to timing accuracy of shock tube detonators. A recent study was conducted to study the timing accuracy of non electric shock tube detonator systems. A follow up study was then conducted to determine the degradation of the non electric shock tube systems accuracy with time. The follow up study is presented in this paper. Samples of detonators from the initial study were set aside for approximately one year and then tested. The results from the aged detonators were compared to those of the detonators that were tested in the original study. As an extreme case a third set of shock tube detonators was tested using detonators that were between eight and nine years old. The results from these tests are presented as well. Each system was tested at a short medium and long delay time. Statistical analysis was conducted to determine the effect of time on the detonators accuracy. This paper quantifies the importance of regular inventory cycling to help preserve manufactured timing when using non electric shock tube detonator systems.

Jan 1, 2013

By John L. Didlinger

We all hate the paper work in keeping accurate blasting records. Nevertheless, have you ever thought what those records could show you? Think about it. Those records could show you vibrations, noise, and safety problems. They could show you the ratio of powder used and tons produced, the cost per foot, even help negotiations for pricing.

Jan 1, 1997

By Michael Burrell

This project involved the protection of an historic landfill located on the site. Construction blasting was for a permanent access road to carry traffic to and from a new metal processing plant being constructed nearby. The landfill contained materials disposed of during the closure of a Phosphorus plant that had previously occupied a portion of this site.

Jan 1, 2012

By Francisco Sena Leite, Raquel Sobral, Vinicius Gouveia de Miranda, Céu Jesus

"The urgent need for improvements in the control and mitigation of environmental and social conditions associated with the extraction and processing of raw materials is increasingly a demand imposed by legal entities and institutions. Therefore, this present article proposes an improvement of the estimation in the magnitude of the vibrations resulting from rock blasting methodologies in the surrounding areas,incorporating the heterogeneity caused by uncontrollable parameters, such as geological andgeotechnical characteristics. This methodology combines the use of empirical vibration attenuation lawscommonly known and with terrain discretization techniques using Voronoi’s decomposition. For thevalidation assessment of this methodology, the data set collected and compiled is composed by 87 vibration measures collected in 16 sample points in one area of study of which 2/3 of the samples were used to create the model and 1/3 for the validation. Using normality tests for statistical residue analysis,it is possible to infer that this present model has null residual mean, as well as a smaller sum of residualerrors. Comparing the methodology present in this paper with the procedures executed nowadays, areduction of the errors associated with the estimation is obvious, highlighting a better characterization of the behavior of the vibrations associated with rock blasting."

Jan 1, 2017

By Gregory Hempen, Thomas Keevin, Russell Wilcox, William Wild

The Department of Defense Strategic Environmental Research & Development Program (SERDP) awarded funding for evaluation of procedures to mitigate peak pressures and energy flux density in the water column from ordnance being detonated on the ocean floor. The research purpose was to conduct scaled testing to resolve whether a theoretically-viable covering technology was operationally effective in reducing blast effects and the impacts of shrapnel. An additional objective was testing effectiveness of this method for hard-bottom units (rock or coral) and (unconsolidated) sediment substrate.

Jan 1, 2011

By Clara Godoy, Álvaro Dapía, Paulo Couceiro, Pablo Segarra, José Ángel Sanchidrián, Juan Navarro

This paper applies geostatistical tools in Measure While Drilling (MWD) data to estimate the probability distribution of values in all the points of the studied domain in order to assess the continuity of rock classes between boreholes. The analyses carried out by Ghosh et al. (2018) and Navarro et al. (2019) have been used as starting point of this work to classify the geotechnical rock condition in four classes: solid rock, fractured rock, cave- in rock and cavity. From it, an application for the geotechnical rock condition of orebodies have been developed, aiming at characterizing the rock before the charging the holes to minimize unexpected rock conditions and to address issues associated with charging and blasting operations. Such problems are closely related with non-optimal rock fragmentation after blasting.

Feb 1, 2020

By Jorge Cárdenas, José Luis Hurtado

The critical distance determination test through direct recording for the mine in Phase 03 was carried out in January 2024, and in it the vibration and pressure models were obtained for the Sedimentary breccia unit. The method of obtaining the records is based on the capture of individual pressure waves generated by distant loads, sequenced in periods of 600 ms for easy identification. The test set up corresponds to a variation of that used to obtain the vibration model, and uses 08 wells for loads and 04 for instrumentation. The results apply a safety factor of 1.2 and 1.5, being 16,000 PSI and 13,250 PSI respectively. The values are valid for any distance greater than 5.5 m, this being the minimum established between wells for loads according to the configuration defined in the field, also considering that in 5.0 m of instrumentation the section of the drill hole with the sensor called S1 collapsed. The results of the analysis of the test, generated with Heavy Anfo 82 explosive, with a final density of 1.15 g/cc, are presented. The results of the modeling and generation of the graphs and tables presented show behavior in line with the concept of scaled distance. It is important to consider that in water conditions there is a high impact by the condition, which causes the records to be higher than those expected in dry conditions and present less variability. It is for the above reason that the row corresponding to distance with safety factor 1.5 is declared valid. The results are only valid for the rock analyzed, whose medium is homogeneous and constant in terms of lithological composition and that present similar resistance characteristics, fracture frequency and water table levels. As future steps, the objective is to quantify the increase in pressure generated between wells by analyzing time and sequence factors. This analysis aims to explain the occurrence of dynamic pressure events in areas where critical safety distances are observed.

Jan 21, 2025

By Joseph Indeck, Seokbin Lim, Andrew Thompson

In the design of explosively driven penetration devices, understanding the impact conditions between the explosively propelled penetrator and the target is one of the most important steps in optimizing the performance of the device. These impact conditions are especially prevalent when a shaped charge jet impacts concrete, which is not an ideal target material. The specific impact conditions, including but not limited to the impact angle and jet properties, create a great deal of variability that affects the performance and penetration of the shaped charge. The large amount of impurities and voids in concrete, along with its heterogeneous nature and the general strength characteristics, make concrete a non-ideal material for shaped charge jet penetration. These material characteristics lead to a highly non-linear deformation behavior of the concrete target during a hyper-velocity impact.

Jan 1, 2011

By Khushaal Popli, Vanessa Roeland, Brian Hall, Carl Diederichs

Highland Valley Copper (HVC) has embraced an integrated Mine to Mill approach to comminution since the late 1990s. Previous blasting optimization was carried out through adjustments to blast pattern geometry (i.e., reduction of burden and spacing). This approach proved very effective and HVC reduced the burden and spacing of high energy ore blast patterns to what was considered the practical limit that still allowed for efficient drilling and bulk truck loading operations. While mining in the bottom of the Valley pit near the end of the previous pushback, HVC encountered high static groundwater conditions which enabled the transmission of elevated inter-blasthole pressures that had the potential to exceed safe operating limits for initiation products. This risk was mitigated through an expansion of burden and spacing for the high energy ore patterns, reducing the application of blasting energy and increasing the average particle size in Mill feed.

Feb 6, 2023

By Douglas Rudenko PG, Jay Elkin, Siavash Mahvelati Ph. D.

Very little studies have investigated the behavior of cracks in unlined tunnels over long periods of time, especially when such flaws are subjected to blast-induced vibrations. Using a pool of 30+ blast events, a positive correlation was found between the peak particle velocity and peak crack movement.

Feb 1, 2020

By Claudio Lechuga, Carlos Scherpenisse, Juan Rafael Otaiza

From the analysis of drilling process, Block Model information, drilling pattern data and expected fragmentation targets; GBlast® software optimizes the explosive charge design in order to standardize the particle size of each blast.

Feb 1, 2020

By Ph. D. Favreau, Favreau Patrice B. Eng, R. F.

Geology is important in mining by helping to identify the rocks which contain sufficient valuable ore to justify their excavation. Geologists give a geological name to each rock type, so geology is a player in blasting; when a blaster has successfully blasted rock of a given geological name at a former site, and he later has to blast rock at another site whose rock has the same geological name, then his first trial often is the same method as he used at the former site, since the geological name of the rock is the same

Jan 1, 2019

By Hairong Zeng, Matthew Baumann, Shahram Tafazoli, Edmond Chow

Measurement of rock fragmentation has evolved from a completely subjective and manual process to a statistically objective and semi-automated process. However, ultimately, the vision is to achieve a statistically representative and fully-automated process. From the blast optimization perspective, it is critical to receive reliable rock fragmentation results quickly to incorporate into the planning of subsequent blasts. Since manual rock fragmentation measurement methods tend to be time consuming, a fully-automated method is the practical way to meet these requirements.

Jan 1, 2012