Search Documents

By Roger Holmberg, Donald Jonson

The Swedish Standard SS 460 48 66, “Vibration and shock - guidance levels for blasting induced vibration limits”, is based on more than 50 years of experience from blasting close to structures and tunnels. The Swedish Standard gives a method for calculation of guidance values for different types of buildings and ground condition under the building. This is done for every building and structure within a predetermined zone. The guidance levels are for the peak particle velocity monitored in vertical direction. The standard is valid for all kinds of blasting project (tunnelling, quarrying, mining etc.) The guidance levels neither take in to consideration discomfort for people inside the building or structure nor vibration sensitive equipment inside the structure. The paper also presents the Swedish Standard SS 02521 “Vibration and shock - Blast induced airborne shock wave - Guidance levels for buildings”.

Jan 1, 2005

By Billy J. Thorne

The damage model in PRONTO simulates the dynamic fracture behavior of brittle rock. It is based on work started by Kipp and Grady, [lg] continued by Taylor, Chcn and Kuszmaul [I91 [20] and recently.modified by B. J. Thorne (first documented here). The essential feature of this model is the treatment of the dynamic fracture process in rock as a continuous accrual of damage in tension, where the damage mechanism is attributed to microcracking in the rock medium. The fundamental assumption of the damage model is that the material is permeated by an array of randomly distributed microcracks which grow and interact with one another under tensile loading.

Jan 1, 1989

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 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

By Frank Chiappetta, Karl Zipf, Robert Hopler, Brian Stump, Francois Heuze, Bob Martin, Vindell Hsu, William Walter, Craig Pearson

The Comprehensive Test Ban Treaty (CTBT) was accepted for signature at the United ,Nations in September of 1996. It ‘now awaits ratification by its signatories, ~including the United States. After the Treaty is in force, the main concern of the international community twill be to verify that no nuclear test is performed.

Jan 1, 1998

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 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 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 Timothy Stark

Blasters are usually strictly liable for injury or damage caused by flyrock (trespassory invasion) and blast-induced vibrations (non-trespassory invasion). The application of strict liability to non-trespassory invasions has resulted in significant litigation that has hampered the use of blasting and the blasting industry. Stark (2002) proposes that blasters should not be held strictly liable for non-trespassory invasions but should be liable only if their conduct is proven to be negligent. This change in legal standard was proposed because improvements in blasting technology over the last thirty years allow blasting to be conducted without substantial risk of harm to property and thus the amount of harm imposed by a blast can be related to the level of care exercised by the blaster. It is anticipated that a negligence standard will reduce the amount of litigation because a plaintiff will have a greater burden to overcome. To facilitate the acceptance of a negligence standard by a court of law, this paper summarizes the standard of care using the 1977 Surface Mining Control and Reclamation Act, extensive U.S. Bureau of Mines research, and current blasting techniques, such as blasting mats. It is important for the blasting industry to promulgate a standard of care so a judge can feel confident that blasting can be routinely and systematically controlled and if the legal standard is changed from strict liability to negligence a subsequent judge or jury will be able to evaluate the level of care exercised by the blaster. This paper also suggests that the industry and/or ISEE develop and disseminate a comprehensive standard of care that courts can use to further justify a change from strict liability to negligence and evaluate the standard of care.

Jan 1, 2003

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 Larry Schneider

In the construction field and to a lesser degree in mining, flagman are often necessary to move traffic and or pedestrians through work zones. Everyone readily recognizes that they are essential for the safety of the general public and the employees on the job. What is not often considered is the safety of the flagmen themselves. Actually, let’s call these employees “flaggers” recognizing the fact that there are as many women as men doing this job. The first problem we need to overcome is the misperception that flagging is a low skill function that can be done by any untrained employee. The reality is that the flagger works in a very hazardous position with serious responsibility for the safety of his fellow employees and the public at large. And to do this job properly re q u i re s that the flagger receive sufficient training before being sent out to the highway. It is also necessary to convince the flagger of the value and importance of their job in order to motivate them to do a professional job.testing, documentation of both, and accurate re c o rdkeeping are key aspects of HM126F. Of course, training and documentation requirements will vary depending on the type of operation involved, and there may be some differences in the application of requirements depending on your jursdiction. Nonetheless, failure to train and properly document such training can result in heavy fines and/or penalties.

Jan 1, 2004

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 Zvonimir Ester

The course of motorway tunnel under construction was set only 2 m away from the main motorway. The thickness of the tunnel overburden rock was 9 m. During the tunnel construction the traffic on the motorway was not supposed to be interrupted. The tunneling was carried out by NATM with classical drilling of blastholes and by blasting.

Jan 1, 1998

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 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 David Weidner

Public relations, regulatory compliance, determination and implementation of pre-blast inspections, and accurate blast monitoring data are all essential components when conducting blasting operations for a large scale, high profile, urban site development. By working closely with the contractor, an independent vibration consulting firm can provide the commitment of time, energy and resources to tie all of these elements together. When this comprehensive approach is properly implemented, problems often associated with projects of this magnitude can be almost completely eliminated.

Jan 1, 2001

By Wilfrid Comeau

The RICHTER scale is used in classifying earthquake severity. It is an energy scale giving the estimated energy liberated at the source of the earthquake. Earthquake damage on the earth’s surface, for example at the epicenter - spot on the earth’s surface directly above the earthquake, for a given RICHTER number can vary. This depends on the depth of the earthquake focus. Deeper earthquakes will generally cause a lower level of damage at the epicenter but the damage will be spread over a greater area. As mentioned by Randy Wheeler on Blastserve, each successive RICHTER number represents about a 30-fold increase in energy. This scale is open at both ends with “0” RICHTER equal to about 104 Joules. The lowest level detected by sensitive instruments is about 2 on the RICHTER scale or about 107 Joules. The highest-level earthquake detected at 8.9 RICHTER represents a release of about 3 x 101 7 Joules.

Jan 1, 2003

By Ethan Steward, Kyle Perry

Underground coal mines have several dangers, one the most hazardous of which is the possibility of an explosion caused by the ignition of methane gas. To reduce ventilation costs, coal mines have the option to close off abandoned areas that are no longer active with structural seals to keep an explosion from propagating into working areas of the mine. These seals must be designed to withstand different pressure levels based on the potential of the atmosphere behind the seal to become explosive, either 50 psi (345 kPa) for inert atmospheres, 120 psi (827 kPa) for non-inert, and over 120 psi (827 kPa) for special cases. Though seals have been designed to resist the overpressure, none have been evaluated for their resistance to the impact of heavy objects. Underground explosions produce high velocity gasses that, traveling through mine openings, may propel objects in the mine at a high velocity causing them to impact and damage the mine seals. Seals damaged in this manner may no longer hold the pressure they were originally rated for and may fail during subsequent explosions or leak explosive gasses into active workings. To test the effects of impact on mine seals, a projectile generator and two seals have been constructed. The projectile generator is a 12-inch (30.5 cm) inner diameter steel pipe with a 4-inch (10 cm) wall, is 8.5 feet (2.6 m) in length, and sealed on one end. Projectiles are propelled by a charge of black powder with a wooden wad and are held in place by foam sabots in the bore. This system, combined with the large bore, allows firing of many different potential projectiles that may be found in an underground mine at a high velocity into the seals. The velocity of each projectile is measured by an infrared chronometer which can later be used to determine its impact energy. Impact effects on the seals are measured using strain gauges, LIDAR scans before and after impact, high speed cameras, and visual inspection. The focus of this paper is on the projectile generator design and initial testing.

By Edward Barrody

There are wide variations in the values of heats of explosion and detonation as reported in literature. These values are not “stand-alone” or sole properties of the explosives. Specifications of the conditions under which they were determined are necessary to characterize these values. This paper proposes that these values are dependent on their oxygen content and the surroundings their products “work against” upon expansion. Also, the heats of explosion and detonation values can have the same values, but different products, showing that the products can take “independent paths” but have the same values.

Jan 1, 2003

By John Brulia

It has been said that the only thing that remains constant is change. After more than 33 years in the explosives industry, I do not take any exception to that adage. I have seen changes in people, changes in ownership of companies-both small and large, domestic and international; changes in products; changes in the way we use products; changes in the way we handle products; changes in regulations; and last, but not least, changes in our perceptions of threats to our industry.

Jan 1, 2008