Search Documents

By Gordon Revey

Over ten million pounds of explosives are used daily to blast rock in mines, quarries and construction projects throughout the United States. Despite the immense volume of explosives used, serious incidents involving the legal use of explosive materials are rare. Unfortunately, when incidents arise they are well publicized, whereas the great majority of blasting projects-even the most challenging ones—quietly occur without incident or public recognition. Although unfair, media coverage focuses on incidents and/or accidents, and as a result skews the public’s perceptions of our industry. These negative perceptions about blasting profoundly effect our work. Most apparent are the community groups who organize to fight blasting work. However, other impacts are more insidious and have long-term effects on our industry. For instance, planning engineers or government agencies often prohibit blasting to avoid the public’s adverse reaction or because of general fear of blasting impacts. Ironically, as regulations and specifications continue to curtail our industry, the net effect is an increase in the cost of rock excavation. As taxpayers, we suffer needlessly by paying more for government funded construction projects. As blasting professionals we are additionally penalized through loss of work.

Jan 1, 2001

By Stephen H. Chung, Kevin Atherton

The main purpose behind this preliminary study was the reduction of costs while maintaining productivity. Finding a way to achieve this balance without compromising controls on safety and quality of blasting results is of continual interest to the mining industry and of particular interest when ore of lower grade is being mined.

Jan 1, 1998

By Craig Wilbour, John Stimberis, Rob Gibson, Lee Redden

An avalanche is a snow slide. A simple explanation is that the snow on a slope will slide (avalanche) when the snow strength can no longer support its own weight. Snow avalanches happen when the load from snowfall or ram on a snow slope increases faster than the stre n g t h of the bonds between snow crystals. Avalanches can also happen when the strength of a buried layer decre a s e s . Active avalanche control is the intentional triggering of slides. Washington State Department of Tr a n s p o r t a t i o n (WSDOT), does avalanche control to minimize the chance of natural avalanches into traffic. Avalanche control work is done all over the world by: highway departments, ski resorts, railroads, mining operations, utility companies, and other activities threatened by avalanches. The majority of active avalanche control is done with skis, by explosives, or exploding projectiles. Blasting techniques and practices have evolved to fit the specific needs of avalanche contro l . Passive avalanche control is the use of engineered s t r u c t u res such as snow sheds, bridges, or snow supporting devices, to permanently protect a specific location from avalanches. The problem is that these struct u res are extremely expensive. There are a variety of passive avalanche control measures as well as the active m e a s u res used to protect the highway over Snoqualmie Pass. As traffic volume and use expectations incre a s e , m o re extensive passive measures will be needed to keep avalanches from affecting the highway.

Jan 1, 2004

By Luis Valentim, Terry Cousins

The goal of a mine is to produce ore at the lowest possible cost with due regard to safety of pemonnel and equipment. The mining process consists of a number of discrete operations such as planning, drilling, blasting,excavation, transportation and crushing. These processes are interrelated and cannot be considered as separate activities when optimising output and minimising cost. In order to optimise the global costs it may therefore be necessary to increase cost in one area such as blasting design and management beyond the norm.

Jan 1, 1998

By Robert Boehnke, Bernd Mueller

Despite enormous efforts over the last decades there are still many unanswered questions with respect to calculation and modeling of the blast process using appropriate physical laws. Most calculations of explosive charges of a blast design are based on experience, empirical observations or blasting theories with serious shortcomings. This paper presents a new theory for the design and calculation of a rock blast that is based on the momentum. It offers a clear-cut method for the calculation of blast processes. The theoretical results will be compared with on-site measurements by means of a newly developed strain sensor and further measuring equipment. The momentum theory helps better to explain physically the processes of a blast. On the basis of long-term statistical investigations a momentum balance can be carried out with the volume-based blasting momentum and the measurable momentum associated with the muckpile and the remaining rock mass. This type of consideration requires a complex procedure which includes the blastability of the rock masses. Realis tic strain measurements open a new interpretation possibility and judgment criteria for the most probable building damage, the dynamic impact on general types of buildings and also for the blast process itself. The blast-induced stress and the momentum generated could be back-calculated using a geophone profile and the strain sensor. The strain owing to a dynamic impact can be influenced by the changing of the drill-, blast- and shotfiring technique like the until now measured vibration velocity. In this way it is possible today to make a complex preparation, calculation and evaluation of blasts. The new techniques of measuring in connection with the momentum theory bring about an increase of the safety and a clearcut method of improving the blast processes. This procedure offers new possibilities for the precise calculation, simulation and modelling of blasts and resulting vibrations and leads to an increase of the safety as well as economic adaptation of the drill-, blast- and shotfiring techniques to a pre-determined blasting result.

Jan 1, 2003

By Martti Hagfors

Underwater explosions have been used as a test method for the determination of energy content of explosives for several decades. This is the only test method by which shock, gas heave and total energy values can be measured separately. The experimental data can be measured from the pressure-time curves measured by the pressure-recording unit. The shock energy is integrated from the shock peak area and the gas heave energy is calculated from the time interval between the primary shock wave front and the shock wave caused by the first bubble implosion. tb. Bubble period, tb, is the time of first bubble oscillation, the time which passes after the shock peak front to the first bubble peak. The total energy value is the sum of these two partial energies.

Jan 1, 2009

By Thomas E. Brown

Commercd explosives have evolved through this century f?om dynamite through ANFO to the current lines of Water Gels and Emulsions. Water Gels and Emulsions evolved to counter the lack of water resistance and density of ANFO yet maintain its low cost position verses dynamite. Today, explosives must be safe and inexpensive and perform under a wide range of temperatures, function efficiently in wet or dry boreholes and have a good shelf life. Emulsions meet this criterion, which is why they are the current trend products worldwide.

Jan 1, 1998

By Michael Olmsted

Inspection of boreholes prior to blasting can result in cost reductions as well as increases in efficiency and safety. Until recently, borehole inspection was performed in two manners. For simple inspections, a flashlight was used to view the upper part of the hole. More thorough inspections were performed with long tool strings developed for oil field applications. Borehole inspection tools developed specifically for mining and blasting applications have now been developed. Video Cameras developed for borehole inspection have been in service for several years. Now measurement tools are available, developed specifically for mining.

Jan 1, 2000

By Teele Tuuna, Voglers Eesti OÜ

Blasting operations are a strong and important part in any kind of building and mining industry, a shot-firer profession is one of the oldest professions in the civilized world. It still serves an important and ongoing purpose in the modern economy all over the world. Europe, nowadays, values strongly the mobility of workers, the movement of know-how and labor force between different countries inside Europe. There are no borders for most of the everyday professions.

Jan 1, 2018

By Dale S. Preece, J Paul Tidman, Stephen H. Chung

"A discrete element computer program named DMC-BLAST (Distinct Motion code) has been under. development since 1987 for modeling rock blasting (Preece & Taylor, 1989). This program employsexplicit time integration and uses spherical or cylindrical elements that are represented as circles in2-D. DMC-BLAST calculations compare favorably with data from actual bench blasts (Preece et al,1993)."

Jan 1, 1997

By Robert Martin, Brian W. Stump, David P. Anderson, W Scott Philips

Since 1994, various mines in the US have cooperated with research scientists at the Los Alamos and Lawrence Livermore National Laboratories to address issues related to verification of the Comprehensive Test Ban Treaty (CTBT). The .CTBT requires that no country may conduct any nuclear explosion in the future. While the CTBT is a significant step toward reducing the global nuclear danger, verifying compliance with the treaty requires that the monitoring system be able to detect, locate and identify much larger numbers of smaller amplitude seismic events than had been required previously. Large mining blasts conducted world-wide will be of sufficient amplitude to trigger the monitoring system at the lower threshold. It is therefore imperative that research into the range various blasting practices employed, the relationship of yield to seismic magnitude, and identification of anomalous blasting results be performed. This paper will describe a suite of experiments funded by the Department of Energy and conducted by the Los Alamos and Lawrence Livermore National Laboratories in cooperation with the US mining industry. Observations of cast blasting, underground long wall generated coal bumps, stoping, and explosively induced collapse of room and pillar panels will be presented. Results of these dual use experiments which are of interest to the mining community will be discussed. These include 1) variation of amplitude of seismic energy at various azimuths from cast blasts, 2) identification of the extent of back failure following explosive removal of pillars, and 3) the use of single fired shots for calibration of the monitoring system. The wealth of information and discovery described in this paper is a direct result of mutual cooperation between the US Government and the US Mining Industry.

Jan 1, 1997

By AJ Rorke, JD Botes

Presplit blasting in strip mines is aimed at creating a safer wall to work under during the coaling operations. Good quality presplits are also necessary for effective throw blasting and drainage of the blast block. A less obvious but important function is full coal recovery. Optimum Colliery has been experiencing rock freezing against the presplit highwalls. The rock formed in patches along the highwall and trapped coal beneath it. The material that was &ozen comprised the rock between the back row of holes and the presplit and was often up to 3 m thick (the stand off distance between the back line and the presplit). The cozen rock formed predominantly along the bottom halfor bottom two thirds of the highwall. Along the top portion of the highwall, the presplit crack was usually well formed with visible barrels. This problem, or similar variations of it, is common on many South African strip-mine operations. Investigative work was carried out at Optimum Colliery to correct the problem. This paper presents the information and measurements that were made and discusses the solutions that have been applied to solve the problem. It was found that there were two independent causes for the tiozen material, with each contributing more or less to the frozen rock along the highwall. It was found that the presplit was not forming properly in places, especially closer to the bottom of the highwalls. The reasons and the solutions are presented. The second cause was found to be associated with reduced detonation velocity in the back line holes coupled with low confinement from long delay periods. Emulsion explosive that is sensitised with air bubbles was found to be prone to this phenomenon near the back of high-energy blasts. A change in the explosive formulation in the back-line holes, together with reduced delays in the back line, has resulted in significant improvements. The details are presented in this paper.

Jan 1, 2000

By Richard R. Brochu

At the International Society ofExplosives Engineers Annual Conference held in Nashville, Tennessee in February 1995, a Seismograph Standards Committee was established. The purpose of this wmmittee was to develop objective performance specifications for vibration measurement instrumentation and field use practices. It was also understood that due to geology, temperature, and moisture in the soils, it is not possible to design and build an instrument to give ‘results which are absolutely comparable for ground vibration. It was, however, considered essential to standardize instrumentation by which vibration can be measured under closely defined conditions so that results obtained by users of seismographs are always the same ,&thin stated tolerances.

Jan 1, 1998

By Larry: McAnuff Schneider, Edward Walter, Gordon Shaw, Daniel Grieco, Dennis Clark

During the 1998 Annual Conference of the International Society of Explosives Engineers (ISEE), the Seismograph Section established a subcommittee for the purpose of compiling a list of all regulations pertaining to limits imposed on ground vibration generated by blasting. The goal of this project was to determine the vibration regulatory levels being enforced, with the further intention of examining their scope, and uniformity. A secondary purpose was to evaluate the consistency of the existing regulations with the current scientific findings on structural response and damage potential.

Jan 1, 2001

By Jeffrey L. Dean

Now in its twenty-fifth year, the ISEE has grown to more than 4000 members representing 75 countries. The Society and its 35 chapters in the US, Canada and Australia work to educate the public about our industry, provide forums for the exchange of explosives technology, serve as a repository of explosives information, offer expert help to governments, develop standardized methods and terminology, and promote research and education by, creating and conducting certificate and trainktg programs and encouraging the teaching of the safe and controlled use of commercial explosives.

Jan 1, 1998

By Calvin Konya, Anthony Konya

State and Federal construction specifications require the Blasting Contractor to prepare a Master Blasting Plan which is reviewed by the Owner’s Representative. The Master Blasting Plan requires the Contractor to submit the design of a typical blast. Most blasting specifications also require the Blasting Contractor to submit Daily Blasting Plans. The Master Blasting Plan and the Daily Blasting Plan require that the Blasting Contractor also submit the types and quantities of explosives and initiators used. The specifications also request that the Blasting Contractor submit the pounds of explosive used per delay for both production and presplit blasts. The Blasting Contractor may also be required to predict the anticipated ground vibration and air overpressure levels for the proposed blasts. There are equations that can be used to predict the ground vibration. There are also equations that can be used to predict the air overpressure levels. The data for these equations were primarily derived from quarry and surface coal mine and some construction blasts. Data from major construction projects were analyzed in this study to determine new air overpressure propagation equations for construction blasting. These new prediction equations compare calculated results analyzed from field data with other existing air overpressure prediction equations. Production blasting air overpressure values are also compared to air overpressure from presplitting

Jan 1, 2015

By Earl C. Hutchison, Wade C. Hutchison

T 0 effectively evaluate property damage that is claimed to have been caused by blasting activities and in order to lay the proper foundation to build the best legal defense, identification of the actual causation for the damages are necessary. For the past twenty years, engineering personnel from VCE, Inc. (previously Vibration Control Engineering, Inc.) have been evaluating claimed blasting damages with pre- and postblast inspections, with analysis of seismic levels, blasting amounts at given distances, and with other engineering considerations. In addition to these evaluations, they have also documented other causes for damages which are of the types that are often claimed as blasting damage.

Jan 1, 1995

By William Wilkinson, Vladisla Kecojevic

Current three-dimensional (3D) computer design technology leveraged into drill and blast planning and operations is changing the way engineers and operations approach drill and blast design. Additionally, Global Positioning Systems (GPS) technology that is now readily available to the civilian population is being implemented into the mining sector with a variety of new products specifically designed for drill and blast operations. The objective of this article is to discuss the steps involved with 3D Computer-Aided Design (CAD) of drilling and blasting, and the benefits such a design can provide in conjunction with GPS and drill monitoring systems.

Jan 1, 2004

By Richard Goodridge, Stephen Thomsqn, S Rodgers, D Tunaley

The mining, quarry and construction industries are facing’new challenges everyday. These challenges can be imposed by economic objectives or through external factors such as extreme geological conditions. Simultaneously, all mines, quarries and construction sites are facing more and more stringent environmental requirements.

Jan 1, 1998

By William C. Geitz

"Lightning has always posed a serious threat to blasting operations, especially wkhin the mining and construction industries and operations involving the manufacture, transport, storage and handling of explosives. In recent years, technological advancements in communications systems and microprocessors have significantiy improved the accuracy and efflliency of lightning detection and warning instrumentation. These advancements have increased the availabilii of highly reliable,accurate and affordable systems for use within the explosives arena."

Jan 1, 1991