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By Joseph Haid, om, Rio Yang, Kelly Fleetwood

Some coal mining operations in the Powder River Basin are currently observing a number of blast holes detonating sympathetically within their cast blasts. Sympathetic detonation can cause poor cast results, high blast vibration levels, excessive back break and fly rock, along with a number of other undesirable blast results. The reduction or the total elimination of blast hole sympathetic detonation is of paramount importance to the coal mining companies operating in the Powder River Basin. This paper describes a systematic approach to prevent cast blast holes from detonating sympathetically through the use of the electronic initiation and expanded blast patterns. In-situ measurements outlined in this paper were recorded from pressure probes, velocity of detonation probes and near field accelerometers, along with digital images generated from a high speed CCD camera. Large diameter angled drill holes were also checked for any measurable amount of deviation by a cable type borehole measurement tool. The field measurements provided the scientific evidence, statistical data, and documentation necessary to develop a sound method or a “road map” that would minimize and in some situations prevent the occurrence of blast hole sympathetic detonation.

Jan 1, 2005

By John Yenter

"Unique blasting problems during reconstruction and expansion of 100 year old buildings toaccommodate gambling. Located on steep mountainous terrain and linked by narrowroadways, the towns of Central City and Black Hawk challenged blasters to exceptionalmeasures in order to control over_break, vibration, public exposure and damage to thecharacter of these historic mining towns. Utilities were also upgraded to fit demands of asmuch as 800% volume change in one year."

Jan 1, 1993

By Rundqvist

The best method to minimise disturbances from traffic to the neighbourhood and in Urban is probably to go underground. For obvious reasons this will cause vibrations, noise and other environmental effects which need very strict regulations and quality assurance in order to complete the work successfully. One project is “Southern Link”, a part of a ring road system. The system of tunnels includes 16 kilometres of tunnels right beneath the south part of the city of Stockholm. At least 20.000 people will be or could be affected by different kinds of disturbances and pollution such as vibrations, noise, gas and groundwater. Another project is the “Arlanda Link”. A new railway with three stations has been built under the existing and running to Arlanda airport with its terminals. Authorities have carefully judged these projects, which cause complaints from neighbours due to disturbances. The blasting operations are professionally managed by the contractors and controlled by consultants to keep the regulations according to the Swedish standards, which are well described in the tender documents by risk analysis and technical descriptions. In spite of that, one conclusion is that it is not always possible to go underground without exceeding stipulated regulations with existing technique. Some of the regulations also double the cost of excavation

Jan 1, 2001

By Larry R. Fletcher

A misfire results when explosives fail to detonate as planned during a mine blast. Accidental detonation of misfires is a frequent cause of personal injury, equipment damage, and lost production. In an effort to minimize these problems, the Bureau of Mines investigated the causes of misfires, methods for detecting misfires, and procedures for their disposal. During this investigation, input was obtained from explosives suppliers, mining companies, blasting contractors, blasting consultants, and governmental agencies. Additional data were obtained through detailed analysis of blasting accidents involving misfires.

Jan 1, 1983

By Richard Brummer, John Hadjigeorgiou, Patrick Andrieux

Some of the major challenges associated with underground mining at depth and/or under high extraction ratios are related to the resulting high stress levels, which can lead to the failure and collapse of the rock mass surrounding the excavations. Sudden and violent failures, which can have severe consequences, represent the highest degree of difficulty in terms of underground personnel exposure, erratic and unpredictable production, ground rehabilitation requirements, possible reserve losses and overall mining costs.

Jan 1, 2012

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 Jerry Wallace

A highway bridge demolition project to allow shipping access to a new container port in Puget Sound ran into trouble when contract-stipulated mechanical means of demolition failed. Blasting was then employed under less than ideal conditions and was successful.

Jan 1, 1999

By Walter Voglauer, Elisabeth Zechmeister

Five serial photos show the first second of the demolition of a 75 m high, reinforced concrete tower in the 23rd District of Vienna, Austria. The tower demolition with high explosives was necessary because a 175t excavator could not finalize the destruction with mechanical tools. All mechanical works in preparation of the blast, such as the borehole drilling, were done by civil companies under the responsibility of the contracted demolition company PRAJO. The blasting itself was planned and executed by the engineer corps of the Austrian Armed Forces, Sunday, May 26, 2013. Nearly 800 boreholes filled with more than 100 kg of military plastic explosives were initiated with about 1,600 Austin electric delay detonators in exactly 1,000 ms and 30 steps of delay. The 10,000 tons of reinforced concrete tower fell as planned without any damage to the environment. Photo 5. The rest of the detonators initiate the water pools filled with high explosives forming a bizarre white water front to fight the following strong development of dust. The first 1,000 milliseconds are over.

Jan 1, 2015

By W. J. Birch, M. Kirke

Despite increasing competition from mechanical methods of tunnelling, the drill and blast method is often still the most viable method of excavating tunnels in strong and abrasive rock. To advance a tunnel using drill and blast, explosives are loaded into boreholes in the rock and detonated according to a prearranged sequence. On detonation of the explosive, the rock is fractured and displaced from its original position, leaving behind the desired void. Among the secondary effects of a tunnel blast are ground vibrations caused by elastic disturbances that propagate away from the blasted tunnel face. The possibility that such ground vibrations may cause permanent damage to property and substantial nuisance has generated significant opposition to the use of drill and blast, particularly in urban areas. It is therefore essential that the blasting engineer is able to predict Peak Particle Velocity (PPV) vibration levels at locations in the vicinity of the blast site. Such predictive capability enables the engineer to design blasts so as to ensure that ground vibrations can be kept within acceptable levels. The objective of this project was to analyse data obtained from the ground vibration monitoring program undertaken during the drill and blast excavation of a hard rock tunnel in Central England. Seismograph recordings of tunnel blasts contain a vast amount of information that cannot possibly be expressed using a single PPV value. The main focus of the study was to investigate whether predictive capability could be improved by using scaled distance models derived for selected PPV components relating to specific detonator timings in a given tunnel round. This study has established a method of analysis that can unlock this information for predictive purposes. By permitting the extraction of sub-event Peak Particle Velocity (PPV) values and allowing Scaled Distance (SD) models to be derived for individual period numbers or groups of period numbers, the method has the potential to vastly improve PPV prediction from tunnel blasting. The method established could also help diagnose blasting problems and help target blast design modifications, resulting in improved efficiency and excavation rates.

Jan 1, 2005

By Lyle Dennis

Emphasis on increased production while maintaining rigid quality standards has necessitated a change in blasting technology at Dacotah Cement's limestone and gypsum quarries. The following three methods implemented during the past three years have yielded an increase in production through improved fragmentation.

Jan 1, 1996

By Steve Dillingham

The horrific events surrounding September 11th left Americans with a feeling of sudden helplessness...the shock of being unprepared and powerless. From this tragedy, we can understand the need to prepare for the unexpected, and can apply this hard lesson into operational planning for those involved in the commercical explosives industry.

Jan 1, 2003

By H. S. Venkatesh R. Balachander, G. C. Naveen

During the construction of a 1020 MW underground hydroelectric project in Bhutan a huge rock fall took place in the Downstream Surge Chamber (DSC) during March 2016. The total quantity of rock in the fall area is estimated to be about 1,50,000m3 (2.6 billion cubic feet), out of which about 25,000m3 (0.44 billion cubic feet) of muck was removed. The removal of muck was stopped apprehending that the cavity formed due to the rock fall may get further aggravated leading to widening and destabilising the adjacent transformer hall cavern or it might day light as the top cover was about 190m (623 feet). As the fall has virtually blocked the 314m (1030 feet) long cavern and divided it into two different chambers (south and north), and that the muck cannot be disturbed, it was decided to erect concrete wall on either side of the fall up to the cavern roof and then later address the filling of the cavity with appropriate fill material. As the access to the DSC was there for the southern side it was decided to extend a cable tunnel which was terminated at a distance on the north side of the cavern by D&B so that once it gets punctured into the north wall of the DSC it can be used to access the fall from this front too. This is a unique situation where in every blast approaching the DSC, the parting between them is diminishing and hence the tunnel blast will be exerting axial load on the parting wall leading to dynamic transient loading conditions and buckling may take place on the northern wall of DSC. This paper describes the various drill blast combinations adopted for successful excavation of this tunnel.

Jan 1, 2019

By Rodney D. Lamond

The need for blast vibration monitoring can be attributed to a combination of three factors: Structural damage, Blast design and Human annoyance. Traditionally, vibration damage criteria are prescribed in terms of peak particle velocity (PPV), as measured or predicted in the ground surrounding a blast. The PPV in the vicinity of a blasthole is strongly influenced by the quantity of the explosive per delay. In general, the existing prediction models give reliable results but fall short of addressing the change in PPV when the charge is decoupled and/or distributed.

Jan 1, 1995

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 Suresh Menon

The explosive industry in India has passed through various stages - from a period of total dependency to a period of self sufficiency and now, is saddled with large spare capacity. The last decade and a half saw the emergence of small scale manufacturers, which until then was thriving on International technology.

Jan 1, 1998

By Jeff Hammer, John McGregor

"The Twin Tunnels, originally constructed in 1964, have become a major choking point for trafficheading up to and returning from the Colorado high country along the I-70 corridor. To increase traffic flow, the Colorado Department of Transportation undertook the first widening of the East Bound Tunnel in 2013. After the successful completion of that project, CDOT began the widening of the West Bound Tunnel in 2014. Both projects had a limited schedule for tunnel construction of just nine months. The innovative blasting and demolition of the existing tunnel lining was a crucial component to the success of both projects. During the construction of the West Bound project in 2014 a large amount of surface bench blasting using conventional methods ran concurrently to the West Bound tunnel excavation to allow for enough room for the new tunnel portals."

Jan 1, 2016

By Gary Kahn

In this document the VODR is discussed from a technical point of view and is intended to give the reader a feel for the design of the instrument, its technical specifications, and its limitations. It is not intended as a tutorial on the use of the instrument in the field.

Jan 1, 1989

By Jack Eloranta

To improve control of blasting, tests were performed to assess non-electric cap accuracy. Simultaneous testing using a Velocity of Detonation Recorder (VODR), Red Lake Lo-Cam and an Instantel DS-677 blast monitor was done. Favorable comparisons were found in the three records . This testing confirmed the accuracy of an inexpensive and expedient cap testing procedure.

Jan 1, 1992

By Michael Ostrowski

While the words “explosives” and “blasting” cause insurers to become apprehensive, skilled contractors using modern techniques under controlled conditions rarely cause serious damage or injury. However, blasting operations frequently result in complaints and, consequently, insurance claims. The purpose of this bulletin is to inform construction project participants of some of the measures which may be taken to reduce losses arising from blasting operations.

Jan 1, 2003

By Larry Schneider

In recent years, many individuals looking into the future of the blasting industry have predicted that the most likely next technological breakthrough would be the use of high precision, digitally controlled detonators. This seemed logical since not only was there much room for improvement in this area, but any significant improvement in delay timing could yield great benefits in productivity and control of adverse effects. And in fact, within the past two or three years, such electronic detonators have been introduced in the field by a number of different manufacturers. These systems are currently being used in many routine blasting operations around the world which are being closely watched and evaluated.

Jan 1, 2006