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By Eduardo Lozano, Vilem Petr

This paper provides an overview of a new method for avalanche control using a high explosive charge placed at the avalanche runout zone: the case charge technique. This new avalanche control technique is well-suited to mountain roads presenting several advantages over the existing methods: minimum deployment time, low cost, reduced probability of misfires, and decreased operation time in the avalanche danger zone. The research work presented in this paper was conducted via large scale laboratory experiments where the detonation velocity and the blast physical properties were measured. During the charge design, several parameters were controlled: charge mass, diameter, geometry, density, and external confinement. In addition, the effective range of case charges was increased by the use of the Mach reflection for certain topographical situations. Finally, field test results collected by the Colorado Department of Transportation (CDOT) during the 2017 winter season are presented. The CDOT avalanche control crews have adopted the new case charge as the preferred technique in numerous avalanche locations along the Rocky Mountains roads.

Jan 1, 2018

By Patrick D. McLaughlin

Crater blasting techniques have had relatively little application in the surface mining industry. This is not surprising, considering the geometry required to efficiently use cratering. The more widely known blasting operations that employ some form of cratering are listed below.

Jan 1, 1992

By Ed Billington, Mike Shields

The trail blaster is faced with a wide range of workrelated challenges, not the least being the work setting itself. It is usually remote, being anywhere from 5 to 30 or more miles (8 to 50 km) from any road. It may be in mountains, high rock desert, or coastal rain forest, and can range from sea level to over 12,000 feet (3700 m) in elevation. The blaster may be part of a 2-person clearing crew, a 4-person maintenance crew, or a 10-person construction crew. The crew will usually be mobile, moving and working up to 10 miles (16 km) or more per day, relying mostly on their own backpacks to move camp, tools and supplies from site to site. Periodic resupply may be by helicopter, aird rop, or even “sherpa” groups, but most often will be by packstrings of horses and mules. The crew goes into the backcountry a n y w h e re from two weeks to three months at a time, and while there, its members “live the job” 24 hours a day, enjoying baking heat, torrential rain or mid-July s n o w s t o rms along with the truly glorious weather that c o m p e n s a t e s . So who is this blaster? Well, “he” may be she, since some of the top trail blasters are women. He/she will also be more than a blaster: Crews are small, so experienced members must be capable of handling the full range of trail work. Thus this blaster is also a driller, and usually also a bucker, snag faller, rigger, dry-stone mason, log and timber carpenter, bridge builder, mule p a c k e r, small-engine mechanic and, not least, camp cook capable of putting out a hot meal from a campfire , in a downpour, in the dark. Being in remote locations, often without reliable communication to the outside world, trail crews enjoy a remarkable degree of independence from “supervision.” With that comes the responsibility to make sound decisions which expedite the work, while promoting crew safety and welfare .

Jan 1, 2004

By R. Franfield

This paper describes a situation that many drilling and blasting contractors have found themselves in – a client?s fear of the use of explosives. In the summer of 2007 Blasting Services Ltd was asked to undertake some drilling and blasting work in an abandoned quarry that was being restored for a housing development. Previous quarrying operations had left a series of overhangs that were considered unsafe and required removing. The site contractor considered that the best and safest way to carry out this work was by drilling and blasting. Blasting Services Ltd, with the technical assistance of Exchem Explosives, designed a drilling and blasting regime to accomplish this work with a series of trim blasts. The design took into account the close proximity of a structure in very poor condition and the imposed vibration limit of 6.0 mm/s (0.24 i.p.s.). The faces were profiled, holes drilled and explosives ordered. A few days before the first blast was due to be carried out the client decided that the poor condition of the nearby structure meant that the use of explosives could not be permitted. This decision was made despite the blast design indicating that the vibration level would be well below the 6.0 mm/s (0.24 i.p.s.) limit.

Jan 1, 2009

By Gary Cavanough, Stuart Addinell, Hector Parra

Drilling deep, straight, accurate holes in hard rock to achieve efficient blasting is a challenge for the mining/quarrying industries with short holes normally drilled using “top hole hammer” (THH) and deep holes using “down the hole Hammer” (DTH).

Jan 1, 2013

By Scott Rosenthal, Kyle Murphy

This paper discusses the trials and tribulations of obtaining Velocity of Detonation (VOD) readings in small diameter blast holes in an underground mine. Montana Technological University (Montana Tech) obtained a time-domain reflectometer (TDR) type VOD monitoring unit. Purchase of the VOD monitor was justified on verifying explosives performance used in Montana Tech’s practical underground mining class and provide a teaching aid for the school’s rock fragmentation class. Before demonstrating the unit to students, we figured we better learn how to use it first so we give the students an appropriate experience. Our first learning was in obtaining the correct coaxial cable for the VOD monitor and how to properly terminate the cable. Once the cable was on-site and terminated, VOD testing could commence. Use of the VOD monitor was tested underground in small diameter holes (1.5-inch, 38 millimeter) pneumatically loaded with ANFO. After a few failed trials, and follow-up discussions with the supplier, VOD readings were obtained for the ANFO loaded holes. Additional readings were obtained for a pre-split product and detonating cord to satisfy our curiosity that the unit was performing as specified by the manufacturer. This paper will share our learnings in the hopes that others can benefit.

By Sadettin Bagdatli, Ali Kahriman, Umit Ozer, Alper Celtikci, Yucel Karakus

Due to population growth and rapid urbanization in Turkey, the need for the construction of residential units, transportation and infrastructure facilities has become increasingly more pressing. Since rock units encountered in the surface and underground in the construction of the subway, infrastructure and housing facilities, it is a necessity to use blast excavation methods. In recent years, large housing construction projects have been carried out especially in Turkish metropolitan areas, involving foundation excavations giving rise to great amounts of earthmoving. Since rock units encountered during foundation excavations are usually hard and solid, excavation with conventional machinery proves to be inadequate and unproductive, hence the necessity for the application of blasting technology.

Jan 1, 2014

By William H. Highlands

Lightning is a natural phenomenon which poses a potential hazard to people, structures, and equipment unless adequate protection is provided. The type of protection required is related to the nature and of the facility. The decision making process involves a number of interrelated factors which should be considered when determining the need for protection.

Jan 1, 1989

By Paul Kunze

When a new bridge was needed across the upper reaches of the Yellowstone River in Montana, removing the old concrete bridge piers became an environmental concern for the highway department engineers. The location is about fifty miles downstream from the north edge of Yellowstone Park. The determination was made by the federal and state agencies charged with protecting the resource, that the old piers had to go but the river bed had to remain unchanged. Concerns were expressed that removing the concrete presented the potential for environmental damage to this protected portion of the river. These concerns prompted the state to place stringent restrictions on the contractor in the way they carried out the demolition and disposal of the piers. The reinforced concrete masses had to be removed to an elevation at least fifteen feet below the river bed and every bit of concrete debris had to be removed from the river channel. Explosive removal was discouraged, but the only other options: saw cutting, mechanical or chemical breaking, were not viable.

Jan 1, 2014

By Dan L'Heureux, Joe Haid, Stephen H. Chung

Most coal deposits in Western Canada involve steeply dipping multiple seams. An efficient way to recover coal seams would be to drill through the seams and blast both the overlying and underlying waste material in one shot without disrupting the coal seams while fragmenting the waste rock for easy removal. This requires special blasting techniques as reported by Chung and Jorgenson in 1985.

Jan 1, 1998

By Charles Deacon

The mining industry is constantly taking greater cognisance of their operating costs as a strategy to counter the effects of falling commodity prices. As a result, optimal operating efficiency is more important than ever. One such operation is that of blasting. Considering the relative increasing costs of explosives and accessories it is desirable to optimise the number of blast-holes fired by maximising their individual output. This achievement may now only be possible following the advent of higher technologies in the form of modified explosives and electronic detonators. This paper reviews and introduces some techniques of blast monitoring, types of operations where each is most suited, resulting modifications to blast designs, and identifies some pitfalls to watch out for when analysing the results.

Jan 1, 2000

By Douglas Rudenko

Have you ever had a neighbor complain about a blast one day, but says the next day’s blast was better, even though the Peak Particle Velocity (PPV) increased? How about neighbors that complain about a small trimming shot, but don’t complain about a big production shot? Have you ever reduced the pounds/delay and gotten more complaints ? Mine operators are often bewildered when trying to correlate blast design parameters to homeowner complaints. When complaints come, standard practice is to set up a seismograph in the neighbor’s yard to monitor the blast. Immediately after the blast, the neighbor usually reappears from the house wanting to know the seismograph reading. When told that the PPV was 0.1 in/set, well below damage levels, the homeowner explodes saying “Your machine is wrong”. Perhaps he is right. Understanding why people complain about blasting is not about PPV, it’s all about structural response. People could care less about how much the ground vibrates; they only care about how much their house vibrates. In this paper we will examine the primary factors that control structural response. Through the use of a large array of digital seismographs, the effects of two production blasts on a community surrounding a quarry are studied. The predicted structural response resulting from each blast is calculated at 175 seismograph locations. The predicted response is then correlated to previous research on human perceptibility to vibrations. The results of this analysis and correlation give a better understanding of what the residents actually feel in their homes. The detonations of two single-hole signature blasts are also recorded by the array of seismographs revealing the dynamic characteristics of the geology ‘surrounding the quarry. Once the influence of the geology was understood, blasts were configured to disrupt the natural rhythm of the site through the use of millisecond delays.

Jan 1, 2000

By Adrian Moore, Alan Richards, Andrew Brodbeck

Structural blast vibration limits should be based on the strength of the structure, the stress induced by blasting, and a responsible factor of safety. In this paper a methodology that uses direct strain measurements to determine the stress induced by blasting is described. The methodology has been used to measure strain resulting from blasting, and establish appropriate blast vibration limits on a brick sewer tunnel, an underground mine heading, brick veneer houses, a water pipeline, and transmission tower foundations. An outline is given of the use of the methodology to establish limits for the main entry heading of an underground coal mine, and transmission tower footings. The methodology that is described has reduced uncertainty factors, and permitted the specification of higher blast vibration limits than had been previously used.

By R Yang, M Lownds

This paper reports studies showing the effects of delay scatter on the peak particle velocity (PPV) of blast vibration using a multiple seed wave (MSW) vibration model developed in recent years. The case studies also show the advantage of accurate delay timing on frequency control of blast vibration. The site parameters used in one of the studies are from a case in which the MSW model has been tested and confirmed to yield accurate predictions. This study uses an open pit blast design and a tunnel design in which blast vibrations using electronic detonators are compared with those from pyrotechnic detonators. Mean peak particle velocity (PPV) and the 97.5% upper bound PPV are compared. It is found that both these values increase significantly with the increase of the coefficient of variation of the site parameter. Using an open pit blast design, the modeling shows that electronic initiation shifts vibration energy to the expected frequency for a selected point of interest. However, for the same design of nominal initiation timing pyrotechnic detonators fail to shift vibration to the expected frequency due to its large scatter of timing.

Jan 1, 2011

By Paulo José Costa Couceiro Junior, Manuel Lopez Cano

The biggest Port of Latin America - the Santos Port in São Paulo, Brazil - has been drilled and blasted by controlled underwater techniques in order to remove around 40,000 m3 (52,318 cubic yard) of rock divided in two outcrop rocks: Teffé and Itapema. Underwater pumped explosive, in combination with small cartridges areas, was successfully used in order to reach a target depth of -15m (-49 ft) and a width of 220m (722 ft) in the navigation channel. It was the first time that a pumped explosive was used in underwater blasting in Brazil and it represents a historic benchmark for projects of this kind in this country. The main challenges faced in this project include the control of the ground vibration, due to the necessity to carry out detonations 40m (131 ft) away from the quay wall - where the passenger terminal and the 80 year-old warehouse were located – and the rush schedule available, in order to finish the underwater drilling and blasting phase before the coming cruise season. Therefore, the perfect combination of an ideal pumped product with an effective pumping system has permitted to carry out the project in a record of less time than 3 months (against to the original expected time of 18 months), with all vibration events under control as result of the special ground vibration program carried out.

Jan 1, 2016

By Chulgi Suk, Hoon Park, Hyonsoo Kim, Hakman Kim, Sangho Cho

Dust emission from blast demolition and other construction activities can be a nuisance; it is widely recognized that fine particles less than 10 µm in equivalent diameter (called PM10) may cause health problems. Mist spray systems, such as rain guns, sprinklers, water/surfactant sprays (or foams) etc., are some of the most effective dust suppression methods. A large amount of research has showed that when water droplets are produced in an equal amount to that of dust particles, the airborne dust is suppressed by the agglomeration of dust and mist particles. A method for generating micro-sized mist from water, achieved by the detonation of explosives in the water tube, was suggested and is called the ‘detonationdriven water bag burst system’. There are many experimentally observed limitations of the explosioninduced water break-up process. The water bag explosion tests were simulated using the AUTODYN software, in order to investigate the aerosolization mechanisms of the detonation-driven water and water break-up process into micron-sized droplets. As a result of the numerical analyses, the diffusion direction of water when detonating in the central interior part of water tube was radioactive and significantly stronger than when detonating in the bottom exterior part; this is due to the compressive flow of the volume change inside of the water tube, which resulted from the blasting wave inside of the tube, as well as the reflected pressure on the ground. Blast tests of full-scaled reinforced concrete columns were conducted to verify the effectiveness of the suggested detonation-driven water bag burst system. The water breakdown and dispersion that occurred while blasting the reinforced concrete columns were observed using a high-speed camera, and dust generation was monitored using four density detectors. The suggested detonation-driven water bag burst system showed that the average dust density decreased by up to 7 mg/m3.

Jan 1, 2016

By Tamara Whitaker, James Gunderson, Ruilin Yang

This paper presents the results of a vibration control project conducted in soft overburden at a surface coal mine located in the western United States. The study uses near-field blast vibration monitoring, analysis and modeling techniques developed in house. Accelerometer-equipped seismographs were utilized for near-field vibration monitoring and analysis. Vibration control was achieved through field data regression as well as vibration modeling using the multiple seed near-field blast vibration model (Yang and Scovira, 2007). The regression was conducted between peak particle vibration parameters and the minimum scaled distance per delay. From the regression analysis, the curves of upper bounds for peak particle vibration parameters and charge weight were developed. The dominant frequencies of the blast vibration were also addressed in this project. The regression curves and near-field vibration model guided the blast design to control blast vibration for maximizing the recovery of coal and maintaining mine productivity.

Jan 1, 2008

By Wade A. Narin, James K. Mitchell

Hydroblasting is considered a distinct soil improvement technique from explosive compaction, though the blast designs for the two techniques are similar. Hydroblasting is a three step process developed for densifying unsaturated, collapsible soils, especially loess. The required steps are: prewetting the soil to an adequate saturation, placing and detonating the explosive charges, and consolidating the soil (squeezing the water out of the pore spaces between the soil particles under gravity) to a denser state.

Jan 1, 1995

By Greg Wyartt

In the Pilbara region of Western Australia, an iron ore mine is undertaking a high wall cut-back to improve stability and allow access to deeper ore deposits. Several sections of the wall have been classified geologically sensitive due to unstable localised geology, and therefore an engineered approach to vibration critical blasting was required. The use of electronic detonators allowed multiple signature (seed) holes to be incorporated into a production blast adjacent to the geologically sensitive area, therefore providing baseline vibration data to be used for future modelling with the added advantage of eliminating unnecessary pit closure downtime typically associated with a signature hole program. All subsequent blast patterns also incorporated multiple signature holes to provide additional data and allow continual updating – and therefore improved accuracy - of the blast prediction model.

Jan 1, 2018

By Nikolaos Petropoulos, Daniel Johansson, Håkan Schunnesson

The optimization of the explosive performance is of great importance since blasting is extensively used in civil projects and mining industry. An improved understanding of how the energy from the detonation of an explosive is transmitted to the surrounding rock mass is critical information for the proper selection of an explosive. Therefore, an extensive study was done on the influence of the blasthole diameter on the Velocity of Detonation (VoD) and the detonation front curvature. In this study, pure emulsion was tested in confined conditions to better simulate the behavior of the detonation of the explosive in rock mass conditions. A methodology is proposed for carrying out the evaluation of the explosive performance. The blasthole diameter of the samples varied from Ø 25 mm (0.98 in) up to Ø 65 mm (2.55 in). The confiner was a magnetic mortar cylindrical sample with mechanical properties similar to a rock mass. A streak camera and VoD probes were used to measure detonation front curvature and VoD. The data was analyzed and correlated with the physical parameters of the explosive. Additional to this, the data was further used to calibrate numerical models in LS-Dyna.