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By L. L. Oriard

he Metropolitan Water District of Southern California (MWD) supplies water to some 16 million people in a semi-arid region. Most of this water is imported. Some of the supply lines cross over the San Andreas fault, one of the most notorious and active faults in the U.S. There was a serious need for emergency water in case normal supplies should be interrupted. To fill that need, MWD had to find a reservoir site on the west side of the San Andreas fault, west of the mountains. Because of the distinctive nature of the location, it was necessary to construct a huge “bath tub” by building a dam at each end of a valley, requiring some 115 million cubic yards (88 million cu.m) of fill. In effect, two large-scale surface mining operations have been under way simultaneously. The $2.2 billion project is known as the Eastside Reservoir Project. Because of space limitations, this paper will be limited to those topics which are expected to be of primary interest to explosives engineers, principally related to large-scale rock fill production. There is not sufficient space to discuss the many diverse geotechnical questions related to site selection, geological and geophysical field testing, laboratory testing and design considerations. This brief overview may assist those who might be interested in making a tour of the project site following the ISEE conference.

Jan 1, 2000

By P. Ross, O. Rielo, P. Katsabanis

Selection of delay times to optimize fragmentation has been a controversial topic among researchers and blasting practitioners. The paper reviews all available experimental information, ranging from small and medium scale tests in geologic materials to small scale tests at the laboratory and synthetic materials, simulating rock. Tests have been re-analyzed and discussed in terms of the information they present and the limitation of the testing environment in representing actual conditions. New results obtained from blasting experiments in specimens made of a grout have provided a clear picture of the effect of delay on fragmentation. The grout used has a strength of 60 MPa (8700 psi), density of 2.5 g/cm3 and P-wave velocity of 4000 m/s (13100 ft/s). Each block was placed in a yoke to eliminate unwanted reflections and the desired delay was obtained using the appropriate length of detonating cord between holes or sub-millisecond electronic detonators. Delays ranged from 0.1 ms/m (0.03 ms/ft) of burden to 16 ms/m (4.9 ms/ft) of burden. Fragmentation was obtained using screen analysis of the collected fragments. Delay time has been shown to be a significant parameter affecting fragmentation and back break. Generally larger fragments and less back break was observed at short values, while fragmentation somewhat deteriorated at significant delay times, compared to what was observed at intermediate delay times. The work is now extended to include the effect of energy partition on fragmentation as well as the effect of initiation point and coupling ratio.

Jan 1, 2014

By Thomas E. Lobb, Harry C. Verakis

Blasting is a primary means of extracting minerals and ores at surface mining operations. The domestic consumption of explosives and blasting agents during the year 2001 was about 5.25 billion pounds. Flyrock is always a major concern for the blaster. Flyrock from surface blasting operations has caused serious injury and death to employees and other persons. Injuries due to flyrock and the lack of blast area security accounted for over two-thirds of all blasting-related injuries in surface coal, metal, and nonmetal mines during the period 1978-2002. Selected accidents due to flyrock and lack of blast area security in surface mining are presented in this paper. Incidents related to construction blasting are also described. Techniques to mitigate blasting accidents are discussed. These include proper blast design, driller-blaster communication, inspection prior to loading and firing the blast, removing employees from the blast area, controlling access to the blast area, and using a blasting shelter. An experienced driller could detect potential problem areas such as voids, mud seams, incompetent rocks, and other irregularities by observing the progress of drilling. The drill log should include the details of any unusual or exceptional circumstances noticed during drilling. A blaster may need to alter the loading configuration to alleviate potential problems. Basic blast design is sometimes taken for granted and assumed to be proper for the conditions encountered, but one size does not fit all. It is known from the physics of blasting that the explosive energy takes the path of least resistance. The path of least resistance could generate flyrock, depending on the blast site conditions. A combination of ‘borehole tracking’ and ‘laser profiling’ can assist in improving the design of a blast. The blaster can use these tools to adjust borehole loading to match site conditions.

Jan 1, 2004

By Adrian Moore, Alan Richards

Time window techniques that limit the explosive charge mass being fired within a specified time window (commonly 8 milliseconds (ms)) have been used for many years and are widely accepted by explosives engineers. The 8 ms time window may be relevant for controlling ground vibration for small blasts at close quarters in a high frequency vibration environment. For controlling ground vibration from blasts in a low frequency vibration environment an 8 ms separation between blastholes is arbitrary and meaningless. The 8 ms time window was never intended as a means of controlling airblast. The use of time window techniques will, in many instances, result in airblast and ground vibration levels that are substantially greater than planned, with unfortunate outcomes. The uses of time windows that are inappropriate have been well explained in previous papers. This paper gives further examples of blast designs that satisfied time window considerations but have resulted in substantially greater airblast and ground vibration levels in certain directions, due to wavefront reinforcement or the combined effect of drilling pattern and delay sequence. Techniques that identify wavefront reinforcement, due to the combined effect of drilling pattern and delay sequence, can assist explosives engineers to avoid blast vibration problems that result from inappropriate time window techniques.

Jan 1, 2002

By Virgil J. Stachura, Calvin L. Cumerlato

The U. S. Bureau of Mines is conducting research on blasting methods that reduce highwall overbreak and the associated rockfall hazards. This paper presents the results of tests using a low-density water gel to improve the quality of air-decked presplit blasts at a surface coal mine in New Mexico. The explosive's specific gravity averaged 0.50 and was bulk loaded using a modified truck which injected the gassing agent. Reductions in overbreak and resulting rockfall were achieved in comparison to a highwall presplit with ANFO. The test sections used 15° angled blast holes and resulted in 1,119 m (3,672 ft) of air deck presplit highwall using a low-density water gel which was then compared to 894 m (2,934 ft) of highwall shot with an ANFO air decked presplit design. The total quantity of explosives per hole ranged from 68 to 113 kg (150 to 250 lbs) and the 27 cm (10-5/8in) holes were 19- to 33-m (62- to 108-ft) deep on 5.5 m (18-ft) centers. Periodic visual examination and photographic surveys of the highwall test areas were used to document the amount of rockfall. In addition, laser profiles of selected sections were conducted to further delineate the damage and highwall contour differences.

Jan 1, 1995

By W. Jiao, Y. Yongqi, R. Shan

Soft rock mines are distributed through out P.R.C. And drilling and blasting is still the main method of driving a tunnel in these mines. Traditional smooth blasting has been widely and deeply studied and put into practice in P.C.R since 1970s. But the cartridge and blast hole are both columns, the stress field in the rock around blast hole at the beginning is symmetry around hole axis, and the original cracks in the rock can be activated randomly. So serious overbreak and underbreak at the boundary of an excavation occur often, especially when the excavation is in soft rockmass, and the rates of half-hole marks are generally about 50% in medium rock, and 20-30% in soft rock in Chinese coal mines. For the sake of overcoming the situation, we have been studying directed crack blasting since ten years, and have got some obvious achievements in this respect. Slotted cartridge control blasting in soft rock is studied in this paper. Through model experiments, reasonable decouple coefficient range and slot width are gotten, and unsymmetrical dynamic strain field is analyzed. Through underground test in soft rock with a strength lower than 1OMpa in Dayan Mining Bureau, The results of which the rates of half-hole marks and the nonsmooth grades of the cut contours are 83.3% and 1OOmm respectively have been achieved.

Jan 1, 2000

By Robert S. Mayo

Tunneling, for transportation, began in France with the Milpass Tunnel on the Lanquedoc Canal in 1680. Of course, the ancient miners had been driving tunnels in search of minerals since the dawn of history but this Milpas Tunnel was the first tunnel exclusively for transportation. In England in 1760, the Duke of Bridgewater opened a canal from his coal mines to Manchester, 10 1/2 miles away. At the mine, he drove a tunnel into the mountain so that the miners could shovel the coal directly into canal boats. James Brindley, an untutored genius, was his engineer and this whole transportation system was an instant success and very profitable through the years. Within a dozen years the Duke, again with James Brindley, opened up the Grand Trunk Canal, 139 miles in length with five tunnels. There was one major tunnel on this system, the First Harecastle Tunnel, 1 1/2 miles in length. But this tunnel was too small. It was only large enough for one 7-ft wide boat which had to be "legged" through by boatmen laying on their backs. By 1824 a second tunnel was driven parallel to the first one, but it had a towpath through it for horse haulage. This was the beginning of the " Industrial Age" and tunnels became a very important part of that era.

Jan 1, 1979

By P D. Katsabanis, W Roberts

Commercial explosives exhibit non ideal behaviour which is very difficult to model. The fume spectrum produced by commercial explosives apart from its practical significance for underground mining is of great theoretical importance since it reveals information about the chemistry of the detonation process. Emulsions, watergels and dynamites were tested under various degrees of confinement in an one cubic metre closed chamber. Sand, concrete, steel and copper pipes were used to alter confinement. The degree of confinement was found to significantly influence the quantity (litres/kg of explosive) and the relative proportions of toxic and non-toxic fumes (percent of total fume measured). These results lead to further confinement testing using various rock materials. Fume results, and thus detonation performance were found to be dependent on the type of rock material used for confinement. Materials such as dolomite, limestone, and granite were found to result in a relatively high detonation efficiency of the subject explosive as shown by the distribution of detonation fume products. Conversely materials such as sandstone, talc and massive sulphide resulted in fumes suggesting low relative detonation efficiency. Fumes appear to be a sensitive indicator of the completeness of reactions occurring within the expansion zone of the composite emulsion explosive, while the detonation velocity is relatively insensitive to small variations in confinement. Estimates of sonic velocities of the confining rock materials were found to show no correlation with VOD results. However good correlation between fume results and sonic velocity suggests that the performance of an explosive as indicated by the resulting fume spectrum is affected by the degree of confinement.

Jan 1, 1992

By James Ludwiczak

This paper consists of the conduct of a forensic criminal investigation of the components, construction, use, and functioning of two suicide bombs. As the title states, the task was to form professional opinions as to whether the bombs would work, would cause property damage, and would injure or kill. The bombs were created and installed by a defendant in a Federal death penalty case where the defendant’s daughter was killed in a shootout with the West Virginia State Police. The two black powder bombs were placed under the front seats of the defendant’s automobile and were designed to function by the use of a toggle switch connected to the automobile’s cigarette lighter. The forensic work first consisted of an inspection of the remains of the wiring system and bombs at the Bureau of Alcohol, Tobacco, and Firearms Laboratory, in Ammendale, MD. This was necessary to determine and detail the wire diameter and lengths, the lengths and size of the wire used, the type of toggle switch used, the type of containers, the type of rocket motors used to initiate the black powder, the manufacturer and amount of black powder used in each bomb, and the type, wraps, and amount of duct tape used for the construction of each bomb. Using this data, tests were conducted by duplicating the wiring system and the two bombs to insure that the system functioned properly. Each bomb was duplicated and initiated to observe the violence produced when initiated in the open air. Duplicate bombs were placed under the seats of a similar type of automobile and initiated. The purposes of the tests were to duplicate the bombs, to observe the violence of the initiation, and to observe the damages to the automobile produced by the initiation.

Jan 1, 2007

By B Mohanty

Several parameters such as, Energy, Strength, Brisance, Impulse, and Bubble Energy, are in common use in the explosives industry today to rate commercial explosives in terms of blasting performance. However, this multiplicity of terms, their frequent interchange and their purported one-to-one correlation with expected performance have given rise to a considerable amount of confusion, and have often resulted in unrealistic rating of explosives. In this paper, various theoretical and experimental methods of estimating energy and performance of explosives are discussed and their relative merits examined. These methods include, Computer Code Calculations, Cylinder Test, Trauzl Test, Ballistic Mortar Test, Underwater Test and Model-scale blasting. It is shown, in the light of actual blasting process, that such measures cannot be considered accurate indicators of expected blasting performance as the properties of rock to be blasted are either totally ignored or only partially accounted for in these methods. It is also shown that no single technique alone among those currently employed by the explosives industry can lead to realistic rating of explosives in terms of expected blast results. The need for the adoption of a two-tier rating system, one based on chemical potential "energy", and the other based on blasting "performance" is proposed, and specific approaches to achieve this objective are outlined.

Jan 1, 1981

By D Larson, M Finger

Chemical explosives may become a key element in many of the in situ energy and mineral recovery methods under development. This paper discusses the potential role of explosives in deep rock mining for resource recovery. Several energy and mineral recovery programs described are an outgrowth of the Plowshare Program and Explosives R&D conducted as part of the AEC/ERDA mission at Lawrence Livermore Laboratory. Several important aspects of the use of explosives in deep rock mining are reviewed. First, the status of knowledge of deep rock fracturing to create permeability underground is discussed. Completely contained blasting has not been a widely applied tool used in the mining industry. We conclude that data available on deep rock fracture is minimal and that the mechanisms that control the processes must be understood before technical and economic feasibility can be established. We also discuss the unusual problems in the selection of an explosive or blasting agent for deep rock applications including emphasis on the functioning at depth and safety aspects. Finally, a brief review of similar activities within the U.S. is given.

Jan 1, 1976

By Lawrence Mirabelli, Wayne Lidkea, Mario Paventi

On Januarv 1, 1996, INCO Limited, Tamrock OY, Dyno Nobel and CANMET formed a consortium for the development of robotic mining equipment called the Mining Automation Program (MAP). This project was a tive- [5] year research and development program that combined the talents of the above organizations to facilitate the development of mining equipment and systems for tele-remote mining. The year 2000 brings MAP to conclusion with actual production process trial testing of the developed prototype equipment and systems during the period between May and October. MAP consisted of multiple projects all of which are based on the communication system developed by INCO Mines Research and currently sold and marketed by Automated Mining Systems Limited. The main projects include the development of a positioning and navigation module (including a software mapping system that will be inherent to each piece of equipment), robotic systems for underground development and stoping operations, as well as software systems to support the use of this equipment. Included in the program was the establishment of a Research Mine, at INCO’s 175 orebody, Copper Cliff, Ontario, Canada. This facility allowed for the on-site collaboration between the companies and research organization in the design and testing of techniques and equipment to mine with TeleminingTM. Some of the prototype equipment developed through the program are: a tele-operated drilling jumbo, a tele-operated load-haul-and-dump [LHD] tram, a tele-operated production drill, a remote initiation system for programming and detonation of electronic detonators, and the development of a vatiable energy bulk emulsion explosive system, including loading equipment, to deliver the explosives to boreholes. Use of tele-operated and automated equipment for mining mandates a dramatic change in the traditional drill/blast/muck/support cycles in the underground mining process.

Jan 1, 2001

By Mark S. Stagg, Steven V. Crum, Stephen A. Rholl

As part of its ongoing research concerning rock fragmentation by blasting, the Bureau of Mines has undertaken a series of test blasts where six cylinder-shaped pieces of granite rock were fragmented using high explosives. The tests were intended to: 1) Establish a dataset that could be used in the development and verification of theoretical models that simulate rock blasting and 2) To add to the fragmentation data currently being collected by Bureau researchers. The cylindrical geometry was chosen so that the fragmentation could be directly compared to two-dimensional computer simulations that assume an axisymmetric configuration as well as more sophisticated three-dimensional models. The granite cylinders, Carnelian granite and Charcoal granite, ranged in size from about 0.46 meters (18 inches) to 0.58 meters (23 inches) in diameter by 0.91 meters (36 inches) to 1.52 meters (60 inches) in length. Physical rock properties tests performed on the Charcoal granite cylinders indicated that the rocks did in fact have similar physical characteristics. PETN-based detonating cord and dynamite were used as the explosive charges and estimates of the values of some important physical properties are given. For the first five tests, the blasted rock was contained by a heavy rope mat suspended inside the Twin Cities Research Center's blasting shelter. The fragments from each of these shots were sorted and weighed to determine the corresponding fragment-size distributions. Even though different types of granite and cylinder sizes were used, similar fragment distributions were produced from shots that used a similar explosive, in this case the PETN-based detonating cord, and comparable burden-to-charge diameter ratios. Significantly coarser fragmentation was produced from a blast that used dynamite as the explosive charge. Fragment velocities were calculated using photographic data from the sixth test which was shot unrestrained in a quarry and filmed with high-speed cameras.

Jan 1, 1990

By Joseph Meyers

Explosives techniques and technology are constantly evolving and improving, yet basic communication and business skills are not being used regularly. Many potential blasting projects never occur due to simplistic, basic factors, such as a lack of communication. Articulate communication is the key component in the blast approval process, which has changed remarkably from how business was conducted fifty years ago. Imperative to the approval process is communication outlining the safety and benefits of the blasting project. Information and transparency with the stakeholders and the Authority Having Jurisdiction (AHJ) will greatly improve the chances of having a blasting project approved. This open communication starts at the inception of the project when the memorandum of understanding (MOU) is obtained, and involves the AHJ through all steps of the approval process. The blasting industry and regulators must work collaboratively to improve safety, security, regulations and licensing. Implementing state of the art blasting techniques, security, safety measures, vibration monitoring and strict licensing allows the AHJ and all stakeholders to remain integrated and informed, contributing to process approval. Regulatory operators should strive to achieve success thru communication, cooperation and compliance which is accomplished thru continued education and transparency. These steps, combined with regular meetings, has proven to be a benefit to both industry and regulators. Relationships are built through trust, teamwork, transparency and communication –including the take holders and AHJ in the approval process from the inception solidifies these relationships and improves teamwork

By D VanDoorselaere

"Image analysis techniques are widely used for blast fragmentation measurement, and various commercial packages are available for this purpose. These packages are very versatile and serve as a useful tool for optimization of blasting practice. But many times, the results provided by image analysis techniques do not match with sieved and predicted data. This leads to the suggestion that understanding the limitations of this technology is as important as understanding its usefulness and versatility.A study was conducted in two stages:(a) Comparison between the results of image analysis and screened data using laboratory scale muck piles.(b) Comparison between predicted (Kuz-Ram) and measured (Image analysis) blast fragmentation results for several bench blasts.During laboratory work, muck piles with known size distributions were analyzed with the help of image analysis technique. A disparity was observed between the sieved and measured results because the image analysis techniques cannot accurately determine the % of fi nes in the muck. During fi eld work about fourteen blasts were monitored. It was observed that predicted (Kuz-Ram) results rarely matched with measured (Image analysis) results. The Kuz-Ram curves were modifi ed by changing the rock factor so that the Kuz-Ram and Image analysis curves match in the vicinity of the 50% passing size. The pairs of curves (modifi ed Kuz-Ram and Image analysis) were divided into three categories depending upon their differences in the coarse and fi nes ranges. The blast design parameters affecting the difference between the pair of curves have been outlined. The suggestions have been made to better utilize the image analysis system."

Jan 1, 2007

By Fumihiko Sumiya, Yukio Kato, Yoshikazu Hirosaki

Secluential blasting is one of the most popular methods in blasting. tiowever, it is well known that an emulsion explosive can be dead-pressed by dynamic pressure generated by the previous detonation. It is difficult to gain the expected blasting performance due to tb.e malfunction of explosive caused by deadpressing and shock desensitization. Such malfunction of an explosive is undesirable for safety blasting operation. Voids in the emulsion explosives will considerably affect the performance of explosives such as sensitivity, detonation velocity (DV), pressure-resistance and so on. To clarify the detonability and the performance of precompressed emulsion explosives, the DV was measured. Three types of microballoon or micro bubble ; two types of glass microballoon(GMB), resin microballoon@MB) and chemical gas bubble ; were used as sensitizers for the sample emulsion expiosives. The underwater explosion test was carried out to load dynamic pressure into the sample explosives. The dynamic pressure was generated by the detonation of a donor explosive, and the DV of the sample explosives as acceptor was measured by ionized gap terminals. The dynamic pressure level and initiation interval for the donor and the acceptor were chosen as experimental factors. The detonability was carefully investigated at short initiation intervals taking into consideration the interaction between same delays caused by the deviation of the ignition time of the electric detonators. From these experiments, the following results were obtained ; A) The DV of precompressed emulsion explosives was low compared with that of uncompressed emulsion explosives in all pressure conditions. B) The decrease of DV in the sample explosives sensitized by GMB s was larger than that of DV in the sample explosives sensitized by RMBs or chemical gas bubbles. C) The recovery of the detonability occurred rapidly in the sample explosives sensitized by RMBs and chemical gas bubbles. However, a long period was needed for the recovery of detonability in the sample explosives sensitized by GME! s. It was concluded that the type of microballoon and micro bubble significantly influenced the detonability of precompressed emulsion explosives.

Jan 1, 2002

By Joshua Hoffman, Rhys Baker, Tim O’Brien

Numerous agencies in the Executive Branch of the United States Federal Government have regulatory jurisdiction over the explosives industry. These agencies develop the rules by which the explosives industry must operate, and many have the authority to enforce those rules. Likewise, there are entities in the Legislature that have oversight of those agencies and develop the laws that agencies must operate under. These entities in the Legislative Branch are Congressional Committees. Each committee has their respective jurisdictional authority over various agencies and issues. There are several Congressional Committees with jurisdiction over the agencies that govern the explosives industry and they differ slightly between the House of Representatives and the Senate. This paper discusses this division of power as it relates to the explosives industry. Each branch is responsive to the public and the processes through which each promulgates regulation and legislation require public input in different forms. Options for civic involvement for engaging each of these bodies of power in their respective processes are presented. The differences between legislation and regulation are highlighted along with the processes by which each are promulgated. A proper understanding of the governmental mechanics that affect the explosives industry are critical for the industry to be able to be proactive in playing a role in these processes in a democratic way.

By D. Goodings, W. L. Fourney, Bonenberger, R., Uli Leiste

The problem of the maximum depth at which a mine buried in the surf zone or beach zone is a threat to landing vehicles is being studied by Naval Surface Warfare Center (NSWC), Indian Head Division, Naval Research Laboratory (NRL), and The University of Maryland Dynamic Effects Laboratory. The problem was divided into two parts: The first part involves determining how deep a pressure plate mine can be and still detect a vehicle passing over it. This requires determining the distribution of stress within dry and saturated sand when a vehicle passes over a buried mine. The results obtained from that study are presented in a related paper (1). This paper will cover the second part, which entails determining the impulse delivered to the vehicle. This is equivalent to determining the impulse delivered to a plate suspended above the detonating explosive charge and includes an investigation of the distribution of the impulse over the plate. The purpose of the research is to develop a scaling law and/or computational capability which will permit predicting impulse to be expected in the field from tests conducted in the lab. The computational effort is aimed at the development of and confidence in computer codes that can be used to predict stresses and strains in plates due to the detonation of buried mines.

Jan 1, 2004

By Robert A. Cummings, Francis S. Kendorski, Charles H. Dowding

During the summer of 1980, a field project was carried out to determine the stability of the beautiful and dramatic natural limestone pinnacles (locally termed "Hoodoos") at Bryce Canyon National Park, Utah, when subjected to ground motions and airblasts resulting from proposed strip coal mine blasting. The concern arose from environmental considerations associated with the proposed development of a large coal strip mine which would approach within 4 miles of the park. The pinnacles range up to 150 ft in height and are quite slender, producing a fragile appearance. The remoteness and ruggedness of the area required a field camp, and 4-wheel drive vehicles, helicopters, and snowcats for support. Portable magazines were necessary to store the more than 7 tons of blasting agents and explosives required. In conducting the blasting, great attention was paid to environmental impacts. In the field, a target pinnacle was selected and instrumented with mechanical strain gages, and research seismographs that required helicopter placement.

Jan 1, 1982

By Cristian Rodriquez, Fernando Fernandez, Rodrigo Fuentealba, Tom BoBo, Maria Rocha, John Kemeny

This paper describes a case study that was conducted at a new mine in South America. This mine has significant geologic variations that will result in different distributions of hard and soft ore being mined at different periods of time over the mine life. A study was conducted to determine the optimum blast design that will meet the mill throughput requirement of 95,000 tonnes (104,720 tons) per day for the first 10 years of the mine life. As part of this study, field rock mass characterization and laboratory tests were conducted. This includes standard rock mechanics tests as well as rock breakage tests used in mill simulations. The geology of the ore body was broken up into four Geologic Units, and statistical variations in the properties were determined for each unit. Using this data along with the data on the occurrence of the different geologic units over time, simulations were made of the run-of-mine (ROM) fragmentation due to different blast designs, and these results were used in simulating the resulting throughput after crushing and grinding. Four blast designs were considered with powder factors of 0.44, 0.54, 0.64 and 0.94 kg/t. The results of this study show that determining the proper blast design is important in ensuring that the mill throughput requirement will be met over the mine life.

Jan 1, 2015