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By Satish R. Kate

Explosive is a chemical energy, which on detonation is released instantaneously with extremely high speed and under high pressure. It is used to meet the basic requirement for breaking of rocks. The productivity is the function of Drilling, Explosives and Fragmentation. Thus, the quality of explosives (energy content) is the key to get desired fragmentation. The variation in energy of explosives and volume of rock per hole have direct impact on fragmentation and cost of excavation (drilling and explosive costs). With the application of higher and higher energy content explosives, it is possible to expand the drilling patterns, i.e. volume in cum. per borehole. As such, higher drill productivity and higher production from the given number of holes can be achieved by adopting appropriate energy content in explosives, and suitable drill pattern for getting desired fragmentation.

Jan 1, 1998

By R L. Keller

Hong Kong has some of the most restrictive practices regarding blasting than any place in the world. Regulations regarding vibration limitations are 1 in/sec for structures and 0.5 in/sec (or even less) for most utilities; with no recognition of frequency response or adjustment. The Hong Kong Geotechnical Engineering Office has one of the most conservative approaches and protective guidelines for pre-blast assessment of slopes subjected to blast vibration (SEE paper '96). The protective measures to control flyrock generally required by the Mines Division are additionally very stringent. It is not uncommon for the costs associated with protective measures or methods which must be employed to exceed the cost of the drilling and blasting itself - or to waiver blasting application unfeasible altogether. From these restrictions it can easily be imagined how blasting in this urban environment would be most challenging.

Jan 1, 1997

By Damien Bretall, William Fourney

Due to the changing face of warfare there is an ever growing need to protect the underside of combat vehicles from mine blasts. This paper presents a new method to better characterize the pressure profiles experienced by a plate as the blast develops. The explosive deformation of a small-scale plate was recorded using synchronized high-speed digital cameras, and then analyzed using 3D Digital Image Correlation software. Time-varying pressure profiles were input into an axisymmetric FEM simulation by fitting curves to data obtained from tests using Kolsky bars to measure pressures. These were then modified to find possible profiles that produce the measured deformations. It was discovered that the final deformation cannot be determined from only total impulse or peak pressures, and that it is very sensitive to the time and spatial decay of the pressures.

Jan 1, 2009

By R. F. Favreau, Favreau Patrice

"The economy profits from the rock excavated in mines and quarries and the excavations required for the construction of roads and buildings. However such excavations are achieved by blasting withexplosives, and explosions create fly rock and vibrations which in some cases may throw rock far intoinhabited regions and may vibrate buildings excessively in these regions. Society, however, no longeraccepts that their quality of life be disturbed by the risks of fly rock or the perturbation of vibrations.Thus it is important to know how to design blasts that do not cause excessive fly rock or vibrations, and to understand why sometimes a blast does create excessive vibration or fly rock. An article presented at the 2015 ISEE (reference 1) explains how unacceptable vibrations can be avoided, while the present article explains why dangerous fly rock occurs and how it can be avoided. The article shows by rigorous calculations with the blast simulator Blaspa that long range fly rock can be due to short collar or short burden, but mainly it explains how inadequate blasting that allows the floor to rise can cause even further reaching fly rock, a situation not usually recognized by most blasters."

Jan 1, 2016

By Neal Lee, Braden Lusk, John Silva Castro

One of the most common assumptions regarding the use of ANFO versus utilizing 100% sensitized emulsion is that ANFO “turns over” the muck-pile better, due to the “higher gas volume” supposedly inherent in ANFO. This paper examines this assumption and provides quantitative data for analysis. Total gas volume from each product was evaluated using Orica’s I.D.E.X. Code analysis. This analysis was used to determine if gas volume is a significant contributor to differences in fragmentation and movement between blasts utilizing the two different products. A constant drilling and blasting cost per yard for given cut depth, hole diameter, stemming height and rock type was utilized. The cost per yard was held constant by adjusting patterns considering product, accessory, and drilling costs. Photographic fragmentation analysis, dig rates measured quantitatively through production tracking and time studies and qualitative information about the diggability of the blast provided through video recordings were used to evaluate performance. The data collected during the study is presented and recommendations are made regarding the performance of ANFO and Emulsion holding other variables constant for a limited number of blasts.

Jan 1, 2012

By D T. Froedge

At the 1990 Symposium of the Society of Explosives Engineering, D.T. Froedge, President of GeoSonics Inc., presented a paper entitled "Differential Topographic Vibration Isomapping", which detailed the capabilities of GeoSonics' new Iso-Seismic Service. In this paper Mr. Froedge described how one hundred or &ore free-standing miniature seismographs called Micro-Seis Units, randomly positioned around a blast, could accurately reveal the effects of sub-strata geology on surface ground vibrations. The paper went on to note the "regression analysis of scaled distance versus recorded particle velocity" as being an inadequate predictor of peak particle velocity. This is due to the fact that the calculated "regression analysis" formula for any site is predicted on the wars; case assumption because of a homogeneous and symmetrical sub-strata geology, a condition that rarely, if ever, exists.

Jan 1, 1992

By Wayne A. Charlie

An experimental test program being conducted at Colorado State University and involves the study of the behavior of water saturated sands under shock and explosive loadings. The study is being conducted to evaluate potential blast induced changes in dynamic soil properties, soil shear strength loss (liquefaction) and densification of water saturated sands under single and multishock loadings. This paper presents testing and measurement objectives, and the equipment and instrumentation developed to load, measure, record and analyze the transient and long term soil behavior. The laboratory shock facility is capable of generating multi-shock pulses with milli-second rise time, peak stress amplitudes of up to 35,000 KPa (5000 psi), peak particle velocity of 5000 cm/set and peak acceleration of 10,000 g. The field explosive facility subjects saturated soil to controlled explosive loadings. Of major interest is the soil strain and water pressure, both during and after the passage of the stress wave, as a function of peak particle velocity, peak strain, loading rate, soil density, initial confining stress and the number of loadings. Based on data obtained to date, soil densification is due to consolidation following liquefaction.

Jan 1, 1991

By Gour Sen, Peter Bellairs

Blasting conducted in rock temperatures greater than or equal to 55°C (13 1 “F) and / or in rock containing sulphide minerals and their oxidation products can result in unplanned detonations. Blasting practices involving the identification of the affected areas together with the use of speciality explosive products and rigorous attention to quality control are required to safely blast in these types of environments. Sulphide dust explosions occur in some underground mines where the primary blast results in a secondary explosion of the sulphide rock dust which propagates some distance from the primary blast area. This phenomena results in considerable damage and the generation of significant volumes of toxic gasses delaying re-entry to the affected area of the mine thereby increasing both costs and safety concerns. The exothermic reaction between ammonium nitrate based explosives and rock types containing partially oxidised sulphides have resulted in numerous high risk blasting incidents. These reactions can occur at ambient temperatures and often result in premature detonations / deflagrations causing a great deal of consternation at the affected minesite resulting in lost production and considerable expenditure to solve the problem. Rock masses at elevated temperatures can also result in unplanned detonations unless appropriate precautions are taken. This paper discusses each of these hazards, cites some case studies and details appropriate generic safe and efficient blasting techniques for each of the above applications using appropriately formulated explosive products.

Jan 1, 2000

By Evan Jannoulakis, Wilfrid Comeau

Using the Scaled Distance (SD) and the vector sum Peak Particle Velocity (PPVvs) from a single delay, preferably single blasthole, in a shot, a number is derived which has shown itself to be consistently related to blasting efficiency, as experienced by one of the authors of this paper over the last thirty years. The numbers derived by this process range in value over one order of magnitude more or less. This variation, a function of distance, weight of explosive in the delay, blasthole diameter, blast design, powder factor and the geological environment, can be consistently related to two of these factors, powder factor and distance. In actual use the measured "BED" representing good blasting results should not vary by more than + 33 to + 50 percent of the estimated "BED" in non calibrated cases, and + 10 to 20 percent where previous experience is available. Relatively high "BED" values are indicative of poor blasting results while relatively low "BED" values may be precursors of poor blasting results in a shot. There are many variables in the geological environment which can affect the "BED". A case study is presented from a surface coal mining operation in eastern Canada. This case study tries to evaluate the reasons for the variability in "BED" values derived from multi-hole shots. A problem in using "Signature Vibrations" from a single-hole shot to predict blasting vibrations from multiple-hole production shots is identified.

Jan 1, 1998

By Greg Parker

"As the Explosives Industry continues to evolve and condense, those involved, such as Blasters,Contractors, Distributors and Consultants, continue to be challenged by both internal and externalforces. Increased pressure by government agencies, higher safety standards, new levels of technology and mandatory certification programs, are forcing us to expand our awareness and increase our levels of efficiency. These higher standards require increased awareness. Increased awareness requires better training programs and better supervision with emphasis on production and the employee. This means the desire to improve must be instilled from the top down. this paper will explore the current impediments to this goal and discuss the possible solutions for achieving greater safety awareness, increased production and higher levels of personal achievement. Through the use of audio/visual aids, I will attempt to show the discrepancies as well as the solutions."

Jan 1, 1999

By Thomas Leonard, Philip R. Berger, Bryan E. Papillon

Bardon Trimount Inc., a large producer of aggregate, crushed stone, and concrete, was experiencing significant public opposition to its five quarries in the Boston area. It was believed by the authors that this opposition could be significantly lessened if the total number of blasts per week were reduced. Although the blasting company at these quarries, Austin Powder Company, contended that this could easily and safely be accomplished by increasing the size of the blasts, regulations precluded this alternative by limiting the total amount of explosives that could be used per blast.

Jan 1, 1996

By Edward Walter

Rock excavation for tunneling projects occurs on a regular basis in the Cleveland area. These tunnels are being constructed to increase the capacity of the sanitary sewer system. Controlled blasting must be performed to remove rock in a number of phases of the project. The rock excavation for construction of a junction chamber is just one case where blasting is the safest and most efficient method available.

Jan 1, 2001

By David Sprott, Patrick Andrieux

In 1990 the Noranda Technology Centre commenced a project to develop an interactive three-dimensional blast design system using a commercial computer-aided drafting and design package (CADD). The objective was to alleviate the blast engineer from the tedious and time consuming blast layout and design functions normally done by hand. This would allow more time for optimizing blast designs through assessing multiple options. Since several blast design software "tools" already existed at Noranda, the need arose to integrate all the applications into one overall system that shared one common database. The result is BLASTCAD.

Jan 1, 1991

By Randal Martin

Recently, questions regarding the influence of atmospheric temperature and humidity levels on airblast levels have arisen at a number of blast sites. Humidity is alleged to have contributed to high levels of disturbance within communities surrounding blasting. In some cases, local regulatory agencies considered adopting guidelines to specify humidity and temperature ranges under which blasting cannot take place. However, it is normal blasting industry practice not to consider humidity or temperature effects, in the absence of inversions, on airblast levels. When blasting is conducted in the vicinity of residential structures, the influence of weather on the propagation and attenuation of airborne noise from the blasting site is always a concern. Sound naturally attenuates in air with distance from the source. A part of this attenuation is attributed to divergence at the airblast wave front, while the remainder of the attenuation is an accumulation of various factors that include temperature and barometric pressure, absorption in air due precipitation and vegetation, wind and temperature gradients, atmospheric turbulence and topography (Beranek, 1971). Wind speed and wind direction, as well as vertical and horizontal temperature gradients can cause airblasts to focus in local regions surrounding blasting operations and may result in air pressures greater than expected. In fact, wind and temperature inversions can actually increase sound levels with distance from the blast site. Close to the blast site, the effects of inversions may be negligible but may exceed 10 dB at 800 m or greater (Davis and Cornwell, 1991).

Jan 1, 2001

By Daniel Hauer

Blocking. (5) The “blocking” of boulders is a much cheaper way of breaking them up than “mud capping.” It should always be used in preference to that method except when too much time will be consumed by a crew of men waiting for the drilling to be done, as shown in example of cost No. 1, as given under “mud capping.” Under such circumstances the time consumed would be a greater cost to the contractor than the extra amount of dynamite. Then, too, on large thin boulders to drill one hole would result only in breaking the stone into such pieces as would again have to be broken; and the many holes might equal the cost of extra dynamite. Under such circumstances if method (6) cannot be used, “mud capping” will have to be resorted to, to do the work economically.

Jan 1, 2006

By John Watson

The earliest known records related to mining document in dramatic terms the fact that mining methods have undergone significant change over the centuries. Wooden wedges, hammers and chisels, “fne setting”, to name a few, were the frst tools used to extract ore .or quarry rock for civilization. These inefficient tools and unsafe practices have been replaced today with some of the highest technology known to man. At the heart of most mining operations is the blasting program which utilizes one of the most efficient tools ever invented.. . explosives. Ever since they were invented, miners have been searching for more efficient products and methods with which to harness this “tool” and make it safer, reliable, and more eficient to use.

Jan 1, 1997

By Randall M. Wheeler, Kenneth K. Eltschlager

Blasting Seismographs use microphones to measure air overpressure from blasting. The microphone height above the ground has been the object of some controversy. The current ISEE “Field Practice Guidelines for Blasting Seismographs” specify microphone placement within 1.2 inches of the ground or over 3 feet above the ground. In this study, air overpressure measurements were taken at different height intervals and compared. Blasting seismographs constructed to the ISEE “Performance Standards for Blasting Seismographs” were used to monitor construction, quarry, and coal mine blasting. Near and far field measurements were taken to obtain representative spectral and amplitude ranges. The comparative analysis shows that microphone height has negligible impact on air overpressure measurements.1

Jan 1, 2005

By Thomas Zukovich, Robert Morhard, Thomas Gelormino

The ExploTrack Explosives Tracking System is a sophisticated integration platform designed to track explosive products in both fixed locations and mobile environments globally, in real-time, on a 24/7 basis. The system utilizes active and passive RFID (Radio Frequency Identification Devices) installed within or applied upon explosives materials and explosives articles and incorporated within explosives packaging and logistic transport mechanisms. The system is designed for real-time inventory on an enterprise level and also across the globe providing explosives tracking, monitoring and explosives security from manufacturing throughout the logistics supply chain through use. The system can also track and monitor all known persons coming into contact with RFID enabled explosives materials and articles at the production level, at the magazine level, at the logistics level and to final use enabling a complete and real-time auditable chain-of-custody.

Jan 1, 2007

By Rakesh Raghavaraju, Bibhu Mohanty

The paper analyzes the decay of shock pressure as a function of distance from the borehole, and its implication on shock-induced fracture properties of the target rock as the first step in predicting fracture and fragmentation behaviour in a well-characterized rock.

Feb 1, 2020

By Cesar Guerra, Alejandro Rojas, Dr. Jhon Silva, Luis Velasquez

The ANN method is applied to predict the P_80 size in one open pit gold mine in Peru. The ANN was implemented in Matlab programming language, and the results from the ANN are compared with data obtained using photo-fragmentation analysis software.

Feb 1, 2020