Search Documents

By Dr. Zach Agioutantis, Elliott Morgan

The explosives, mining, and heavy civil industries consistently battle the uncertainty that is associated with working with a heterogenous medium like rock in blasting. This has led to studies to increase fundamental understanding of material response under dynamic loading that is associated with blasting. This study looks at the dynamic strain associated with blasting the lab Split-Hopkinson Pressure Bar (SHPB) testing while also building off of previous studies with the goal of better understanding the dynamic forces that are enacted on a geologic body during a blast loading event. This is required in order to advance geologic blast response modeling. This is achieved through analyzing the stress and strain values for each specimen that are calculated from strain data collected with a SHPB. Based on this data, the dynamic material response characteristics are able to be determined. Tests were conducted on five Berea Sandstone specimens with a rough length to diameter ratio (L/D) of 1.0. The strain data from these tests were then used to create stress strain curves as well as charts depicting failure stress to both strain rate and failure particle velocities. The tests conducted returned similar results to previous tests results on Berea Sandstone while also showing a correlation between strain rate at failure and failure particle velocities. While further research is needed, there is evidence that SHPB test data could be used in conjunction with the MBF model. The MBF model states that the peak particle velocity (PPV) of blast vibrations can be correlated with deformation (strain) at a given point. With a further understanding of dynamic material response correlated to PPV measurements, further refinement could allow for better prediction of blast performance.

Jan 21, 2025

By Gary Anderson, J. P. Remi Proulx

Rio Tinto’s Colowyo Coal Mine produces 2.1 million tons per year in northwest Colorado. Colowyo uses the terrace mining method to recover up to seven coal seams ranging in thickness from 5 to 20 feet. Coal recovery in the 6 foot thick high grade C-seam has recently been challenged due to large variations in the pitch and roll of the seam. As well, some coal damage was seen due to an increased thickness of the overburden consisting of a hard sandstone channel.

Jan 1, 2012

By S. Lim, G. Walsh, V. Romero

The cable television show, Mythbusters, contacted the New Mexico Institute of Mining and Technology requesting a pressure gauge to be used in underwater testing. The requirements for the gauge were: it must be passive (i.e. require no power to function), it must indicate when a certain, pre-determined pressure was reached, and that indication was to be visual. A pressure gauge was developed, using standard, commercially available rupture discs, set to burst at 500 psi. Underwater testing was conducted using a 400 lb Pentolite charge. Test devices were set out at ranges from 50 to 200 feet from the seat of the blast. The rupture discs showed a lethal range up to 100 feet, but not at 150 feet. This result matched well with the behavior predicted through modeling and simple shock physics calculations. Additionally, the geometry between the incoming shock and the pressure gauge did not seem to have a strong effect on gauge performance.

Jan 1, 2009

By Y. Idrogo

Electronic delay detonators have been used in most types of blasting application with great success, with the accuracy and precision being used effectively to control negative environmental impacts like vibration. They have also provided consistent repeatable fragmentation and heave results. With the very wide choice in delay period and powerful timing design software, the choice of firing times to optimise blast results is not always clear to the designer. So the improved results achievable from the use of electronic delay detonators are often not optimally achieved.

Jan 1, 2018

By Keith Best

It has been said that when a person does something right no one remembers but when they do something wrong no one forgets. This statement, when applied to the explosives industry, has never been truer. Think about it.How many times have you seen a news crew reporting on how well a blaster is doing his/her job? Normally, all you will see is how bad things are going and how much “damage” is being done.

Jan 1, 2008

By Victor Munoz, Jorge Oliva, Gonzalo Marias

Cerro Vanguardia is a known gold and silver deposit located in the province of Santa Cruz, Argentina. The mine has been in operation since 1998 and is thought to be one of the most important mines in Patagonia. More than 102 epithermal quartz veins have been identified in the area, with variable lengths, thicknesses, orientations and dips that constitute what is possibly one of the most extensive outcropping vein systems on earth.

Jan 1, 2019

By P. E. Hoffman, Joshua Ph. D.

The Institute of Makers of Explosives (IME) led a post-detonation debris collection project in conjunction with a large AN railcar detonation conducted by the Department of Homeland SecurityTransportation Security Administration, Department of Defense-Combating Terrorism Technical Support Office, Sandia National Laboratories, and the U.S. Army Dugway Proving Grounds. This important work will aid in underpinning algorithms used in the IMESAFR (Institute of Makers of Explosives Safety Analysis for Risk) Quantitative Risk Assessment (QRA) tool. The test also provided valuable data about AN detonation characteristics when it is driven to detonation. The test took place at the Utah Dugway Proving Grounds (DPG) on April 27, 2018 and the debris collection was conducted the following two weeks with an average of 20 persons per day and an approximate total of 1,400 manhours. This paper details the collection efforts, challenges, and lessons learned. It also presents some of the initial findings relating to the debris distribution.

Jan 1, 2019

By Adrian Moore, Alan Richards

A real-time system for prediction of the effect of meteorological conditions on airblast overpressure levels has been established in the Hunter Valley Coalfield in Australia. Real-time meteorological data from continuously operating sounding equipment and a predictive meteorological model is input to an atmospheric refraction model that enables the effect of meteorology on airblast overpressure levels in the area surrounding the blast site to be evaluated. Graphical outputs from the model, which are superimposed over a scaled airphoto of the mine and surrounding area, show the extent that airblast levels will be increased. When combined with inputs that quantify the effect of blasting specifications, the airblast levels that will result in the surrounding area from the combined effect of blasting specifications is determined. The model permits those responsible for blasting to make more accurate decisions on suitable times that blasting may take place to conform with applicable airblast limits.

Jan 1, 2009

By Pierre De Pasquale, Gilles Jauffret, Ricardo Chavez

"When blasting in quarries or mines, the main source of inconsistent results is directly related to thenon-homogeneous energy distribution through the rock-mass volume. This variation has differentorigins: drilling deviations, geometry differences from one borehole to another (burden, spacing ...),and inherent geological conditions."

Jan 1, 2016

By Robert Hopler

RBH Note: in 1913 black powder was still dominant as a coal-mining explosive, but permissible explosives were making some slight headway. For example, in 1902 there were only 11,300 pounds of permissibles used in coal mining, but in 1913 the quantity was 21,801,285 pounds. However, there were 187,551,653 pounds of black powder used that year. It took many years before the use of black powder ended in coal mining. From the picture of the miner reparing his explosives it’s hard to tell what he’s using, but the fact that a wooden Du Pont powder box is shown, he’s probably not using black powder. That doesn’t mean he’s using a permissible, either, since that was not yet a requirement. It’s interesting that the miners have open flame cap lamps, and the miner is actually smoking a pipe while preparing his explosives.

Jan 1, 2014

By Leslie Taylor, Uli Leiste

In this paper, results from small scale testing conducted to determine pressure time profi les acting on a plate (taken to represent the bottom of a vehicle) at any given distance from the center of the plate will be presented. These results will be discussed in relation to visual observations of the upward moving sand.

Jan 1, 2008

By Thomas Rupp, Michael Siegwart

The paper presents the vibration and sound emission measurement campaigns carried out in 2007 in preparation for the Ceneri-Basistunnel construction. We also present the vibration measurement campaign conducted during the construction of the Zimmerberg-Basistunnel. Both tunnels form an integral part of the Swiss Federal Railway Company Neue Eisenbahn Alpentransversale project (NEAT). This strategic project comprised the construction of several new tunnels. Its aim is the improvement of the existing infrastructure. The improved infrastructure will be able to accommodate a larger volume of railway traffic that is also crossing the Alps at higher speeds. The construction of the Ceneri-Basistunnel commenced in 2006. Both the Zimmerberg-Basistunnel and the Ceneri- Basistunnel are located underneath densely populated areas. Therefore, noise and vibration emissions have to be kept to a minimum and must not exceed applicable codes of practice. In order to identify the most appropriate blasting strategy for the yet to be constructed Ceneri-Basistunnel, blasting trials were conducted. The paper presents the findings of these trials and identifies ways to reduce both noise and vibration emissions from blasting. The construction of the first phase of the Zimmerberg-Basistunnel took place between 1999 and 2003. While the first phase is already in operation, the construction of the second phase has been postponed (commencement originally due in 2007). The Zimmerberg-Basistunnel connects the outskirts of Zürich with the city centre. As the tunnel site was not located close to the surface near populated grounds, no special measures were needed to reduce the noise emissions from blasting. However during the construction of the tunnel, the vibration emissions from blasting were monitored on more than 50 locations on the surface. The paper presents the analysis of some of the data. An emphasis is placed on the appropriate synopsis and presentation of data for documentation purposes.

Jan 1, 2009

By Pedro C. Carneiro, Luiz G. I. Maciel

"This article presents data of advance and excavation rates in tunnelling works, and how theseactivities interact with the duration and cost of a contract. These key parameters, after analysis andsynthesis, will be used in coming works to ensure the evolution and adaptation of the method created by the Norwegian University of Science and Technology - the NTNU Method - to Brazilianconditions, which will be reflected in the duration and cost of underground drill and blast tunnellingworks."

Jan 1, 2016

By Robert Jacob Cefalo, Rio Tinto Kennecott

At the end of 2016, the Mine started a new ore phase in the section of the pit located on the East Wall. The East Wall geological structures required controlled blasting for peak particle velocity (PPV) frequency vibrations to protect the wall. Frequency controlled blasting using linear seed wave superposition modeling was required and implemented to reduce the far-field affects to the wall. This paper covers the work done by the drill and blast engineering group, controls used to protect the mine infrastructure, and the continuation of work-to-date of frequency controlled blasting for wall stability. The narrow width of the layback required the combination of hole sizes to blast large diameter production patterns with smaller diameter trim patterns in the same blast. A single blast had to use different burden & spacing and hole diameters and required the use of different timings throughout the pattern. Electronic detonators were required to limit blast vibrations and accommodate the specific timings needed to reduce low frequencies. The geotechnical group with the help of geotechnical radars worked with the drill and blast group on creating a tracking and reporting of blast performance. The radar readings informed the drill and blast engineers of the performance of the blast as it related to the long term performance of the highwall

Jan 1, 2019

By Tyler Rockley, Greg Bailey

This paper is an engineering case study of a blast performed on a highly weathered sandstone isthmus in an area sensitive to vibration and airblast, the challenges associated with such a blast, the methods used to understand rock characteristics, the blast design considerations and a discussion of the blast results. The purpose of the blast was to remove approximately 12 feet (3.7 m) of surface material in order to install a pumping station. The isthmus provided several challenges due to the weathering of the rock and multiple open faces with surrounding water. The highly fractured and weathered rock was subject to about ten years of freeze thaw cycles, influx of water and seasonal submersion. As such, all actual rock conditions were indefinite, including fracturing, rock properties, degradation and competency. The isthmus also had immediate neighbors who were unused to the environmental effects of blasting. To help continue to keep the social license to operate in the area, it was important to reduce the ground vibration, blast duration, dust and airblast. These factors required a better understanding of how the rock would respond to blasting. In order to do this, test blasts were performed on the same geologic formation in a different location of the quarry that was less sensitive to vibration and airblast effects, allowing the blast parameters and design to be verified and refined. The test blasts were performed while monitoring vibration, air blast, material movement and overall shot performance, and the blasting parameters were adjusted accordingly. The isthmus blast was performed based on the final design from these test blasts. The drilling and loading of the shot all met acceptable criteria and were comparable to the test blasts. The blast performance, however, was not as expected; the depth impacted by the blast was substantially more than expected. Since the test blasts were performed in the same formation, but in material that was significantly less weathered than the isthmus, the actual effect of this weathering was the only difference between test blasting and the isthmus blast. Thus, these results can be used for future reference to highlight the effects of blasting such highly weathered rock and help instruct the blast design in similarly complex conditions.

By Mick Lownds, Ruilin Yang

The potential advantages of electronic detonators with accurate timing have been increasingly recognized by the blasting community. However, in comparative blasts the results with pyrotechnic timing are sometimes comparable to those from electronic timing. Statistical variation in blast results is a plausible cause of these observations.

Jan 1, 2011

By Dale S. Preece, Ruilin Yang

"Air-decks are often employed for presplitting along the final highwall of a blast and are sometimes also included at the bottom or in the middle of explosive columns in the production portion of a blast. Shock wave physics is an important part of air-deck behavior since the bulk explosives in the column impart a shock into the air-deck where the air shock then passes through the air-deck at a rapidlyattenuating velocity. Through both high-fidelity modeling and shock physics theory it is shown that theresulting pressure in the air-deck is two orders of magnitude less than the detonation pressure of theexplosive."

Jan 1, 2017

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 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 Robert Hopler

CHAPTER I. DEFINITIONS AND CLASSIFICATIONS. Definition of Explosives. SECTION 1. The term “Explosive” or “Explosives” whenever used in this ordinance, shall be held to mean and include any chemical compound or mechanical mixture that contains any oxidizing and combustible units, or other ingredients, in such proportions, quantities or packing that an ignition by fire, by friction, by concussion, by percussion or by detonator of any part of the compound or mixture may cause such a sudden generation of highly heated gases that the resultant gaseous pressures are capable of producing destructive effects on contiguous objects or of destroying life or limb, and includes all the articles specifically mentioned in Section 3 herein, and all other similar articles

Jan 1, 2013