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By G Dean Barrett

Just one year ago at the 1986 Annual Meeting of the Society of Explosives Engineers, Dr. Calvin J. Konya presented a paper entitled "Presplitting Granite Using Pyrodex, A Propellant.'' Since that time more evidence has been developed to support the concept that "...gas energy can be the principal splitting force and that the stress wave or shock wave is not necessary to cause the presplitting action to occur." Work done in Vermont and Georgia is presented, and the ability to split granite without causing radial cracking of the bore holes is demonstrated.

Jan 1, 1987

By Richard J. Mainiero, Michael S. Wieland, Harry C. Verakis

The Bureau of Mines, U.S. Department of the Interior, has been conducting research on delay blasting in underground coal mines in support of the efforts of Mine Safety and Health Administration (MSHA), U.S. Department of Labor, to revise coal mine blasting regulations. Part of the research centered on developing an understanding of the factors that lead to misfires of permissible explosives. Research was conducted to determine whether frequency of misfires was related to borehole spacing. For a wide variety of permissible explosives, misfires were observed for about 50 X of the holes at 45-cm (18-in) spacing. Misfires were also observed for 60-cm (24-in) spacing, but the frequency of misfires was much lower than observed for the 45-cm (18-in) spacing. The Bureau has recommended that hole spacings of less than 60 cm (24 in) be prohibited.

Jan 1, 1986

By Finn Ouchterlony, Gert Bjarnholt, Robert Holmberg

A system for contour blasting with a linear shape charge principle has been studied /10/. In one operation the charge creates two notches along the bore hole wall and breaks the rock mass. The built in notching capability makes it possible to reduce the specific charge and the bore hole pressure to 1/3 of what is used in conventional contour blasting and to ensure that cracks are initiated and propagated only at the notches and nowhere else. The notching capability of linear shape charges has been studied experimentally and the bore hole pressure calculated to aid in optimization of a charge for future field experiments in bore holes with a diameter of about 50 mm.

Jan 1, 1983

By W. J. Birch

The recording of information is critical to the blasting process, whether it be for planning purposes, statutory requirements or environmental compliance. The review and analysis of past data can play a key part in a blast.s design. Statutory records must be held to preserve operational licenses and well-maintained monitoring records are a vital defence for today.s litigious society. However a single blasting event can be responsible for generating vast amounts of data. This information maybe collected pre or post-blast and in their individual ways may have a requirement to be logged, processed, analysed, reviewed and reported before eventually being archived.

Jan 1, 2002

By Young-Dong Cho, Han-uk Lim, Bok-Ki Park, Sang-Eun Lee

Many methods and techniques have been developed to reduce ground vibrations. Some of them are an adoption of electric millisecond detonators with a sequential blasting machine and an improvement of initiating system with an adequate number of delay intevals.

Jan 1, 1995

By Robert B. Hopler

The Hercudet™ non-electric delay blasting cap system has exhibited outstanding performance and economic results in surface work. The versatility inherent in the system, which allows the combining of the built-in cap delays with the tubing delay (i.e.: the travel time of the gas reaction through the tubing), has resulted in outstanding blast results. Examples of blast patterns used, details of the blast design process, and recently-developed methods of use of Hercudet for surface initiation of detonating cord downlines are given in the paper.

Jan 1, 1978

By Donald Jonson

The Arlanda Link project is for the time being the most interesting project in Sweden, concerning rock and blasting technology. The total amount of rock excavated beneath Arlanda airport comprises 800 000 m³ divided in four parallel tunnels measuring a total length of 8,5 km, with a rock covering of only 5-15 m between the tunnel roof and existing terminal buildings.

Jan 1, 1997

By H Y. Fang, H Sutherland, R M. Koerner

Due to the increased number of complaints by property owners to blasting related industries an apparent need for a clearer understanding of blasting-related damage is needed. We feel that direct structural crack monitoring during such blasts is the appropriate measurement technique. Instrumentation and interpretation of results for taking such measurements are described in this paper. Typical results from blasting and other environmental effects are also described which can eventually be related to Fracture Mechanics principles in the hope of clarifying such disputes in an equitable manner.

Jan 1, 1976

By Dave Proudfoot, Mike van Wyk

"There has akvays been plenty of discussion around the ‘accuracy of pyrotechnic detonators withmost recognised manufacturers claiming a variability of arourid 1% or less for their ‘superaccurate’ pyrotechnic based detonators. It is only now being understood that this 1% variabilitycan have serious adverse effects on blast performance. For example a 1% accurate 500millisecond shock tube detonator can fire anywhere between 485ms and 515ms. When wecouple these rather inaccurate ‘accurate’ detonators with short delays on surface, such as a 17millisecond connector, the probability of delay crowding and even out of sequence firing is quitehigh."

Jan 1, 1998

By Peter Bellairs, Anthony Bubb

The Porgera Gold Mine is located at an altitude of 3000m in the central highlands of Papua New Guinea some 600 km Northwest of Port Moresby the capital city. Access to the mine is via a five hour trip on an unsealed road from Mount Hagen the nearest regional centre or 40 minutes via air. The mine operates on a fly in - fly out basis and currently produces ore from both opencut and underground operations with the former providing the bulk of the mill feed. Opencut mining utilises conventional truck / shovel, drill and blast methods on both 10 metre and 14 metre bench heights with the larger benches being restricted to the stripping areas. This paper presents the strategy used and the results of a blast optimisation process in the opencut that was a joint effort between the mine personnel and the explosives manufacturer/supplier.

Jan 1, 1997

By E Castelli, M Fomaro, R Mancini, M Cardu

The economic return of rock blasting is not provided by brute volume of broken rock, rather by the amount of marketable product. That is the case of the porphyry quarries of Trento district, whose output is mainly absorbed by road paving and building facing elements production.

Jan 1, 1995

By Byron Groen, Corry Goumans

Description of Project: Project location is at WAC Bennett Dam in Hudson’s Hope, British Columbia, Canada.

Jan 1, 2014

By Pierre Allard, Wilfrid Comeau

Near-field and close-in blasting can be safe and efficient, near engineered structures, if the dynamic reaction of structural members to blasting vibrations are considered. Safe particle velocity criteria can be derived from allowable safe static flexural deflections and critical frequencies. Control of close-in blasting can be accomplished using low-pass filtering of the particle velocity signal at the critical frequency. The CETE Mediterranee laboratory at Aix-en-Provence, France, a branch of the Ministry of Roads and Bridges has -pioneered this approach and successfully applied it to major road cuts and tunnels in built-up areas, as well as a major powerhouse expansion project in Africa. This approach is presently being used for a spillway rehabilitation project in Quebec, Canada. This paper exposes- the theoretical aspects and gives case histories of its use. The SCS-15 an automated, peak reading, data acquisition device is described.

Jan 1, 1991

By Thomas Palangio, Lyall Workman, Jack Eloranta, Tom C. Palangio

The fragmentation distribution of the blasted ore is an important descriptor of blasting results. Traditionally it has been hard to measure quantitatively. Developments in image analysis over several years makes it more feasible to measure fragmentation before crushing on a continuous basis. Post crushing, mill feed distributions can also be measured.

Jan 1, 2007

By Dale S. Preece, Lee M. Taylor

Computer simulation of the physics involved in conventional rock blasting can be split into two phases; transient stress wave propagation and rock motion. Because the two phases involve totally different mechanisms and time scales, they must be numerically modeled with two different computer programs. The first phase is usually modeled with a finite element or finite difference code which treats the rock as a continuum and simulates the transient stress wave and subsequent fragmentation of the rock. The second phase is usually modeled with a distinct element technique where the rock mass after fragmentation is no longer treated as a continuum but as a finite number of distinct particles that interact with each other through collision mechanics.

Jan 1, 1989

By Bruce B. Redpath, Thomas E. Ricketts

Scaling laws commonly used for describing or predicting blast motions generated by conventional arrays of blastholes are dimensionally incorrect. The scaling of distance by the cube root of charge weight is correct only for spherical charges, and scaling by the square root of charge weight is incorrect for any charge configuration, although both approaches may result in empirically useful formulas for a limited range of charge sizes. Analysis of motions generated by a large set of underground blasts shows that scaling distance by the square root of the linear charge density, which is dimensionally correct for a cylindrical borehole, yields much more consistent results than the traditional scaling rules. Further, this scaling law is valid right up to the free face of the burden. A significant result of this work is that the peak particle velocity for an array of blastholes is primarily dependent on blasthole diameter and not on total charge weight or maximum explosive weight per delay, which are the commonly used parameters for scaling seismic amplitudes generated by conventional blasting arrays.

Jan 1, 1987

By Michael S. Wieland

Delay detonators that are damaged by cross-hole wave interactions degrade blasting work and raise the risk of incidents. Damaged detonators impose risk, because they can retain sensitive explosives that respond to stray energy during recovery, inspection or disposal. Laboratory techniques were developed to rank the ruggedness of delay detonators under replicated field-shooting conditions. The hazards are tremendously magnified if trial detonators are installed directly in secondary explosives to rank initiation strength. Therefore indirect ranking techniques were sought that mitigate the risks without compromising the worthiness of the method. Four types of hardware fixtures, referred to as simulators, were developed to yield distinct forms of transient compression. The shock and rift versions generate compression pulses representative of in situ waveform components. The waiting time, until the trial detonator functions, duplicates typical delay periods. The trial detonator is mounted within water, which has a density and inertial resistance comparable to most blasting explosives. The work output from the trial detonator explosion is registered as fixture wall-expansion. This work output determines malfunction results, regardless of which type of simulator is used.

Jan 1, 1997

By B de Raadt

After discussing mechanisms of collapse for the explosive demolition of towers in general and cooling towers in particular, author comments upon a blasting operation in which four cooling towers were involved. The intention of this paper is to present reliable parameters, generally valid for the explosive demolition of reinforced concrete cooling towers.

Jan 1, 1978

By Mark S. Stagg, Siskind David E

The mining industry occasionally blasts near pressurized transmission pipelines and has requested guidance on safe vibration levels and setback distances. The Bureau of Mines and the Indiana Department of Natural Resources cooperated with AMAX Coal Company on a study of coal mine overburden blasting. Five buried and pressurized 250-ft pipeline sections were specifically installed on the Minnehaha Mine highwall near Sullivan, IN for testing to failure. Four welded steel pipes ranging from 6- to 20-in diameter and one 8-in PVC water supply pipe were monitored for vibration, strain, and internal pressure for a period of 6 months while production blasting advanced up to the pipeline field. In contrast to previous studies of small-scale blasting representing construction activities, these tests involved overburden blasts of up to 2100 lb per delay in 12-1/4-in diameter holes.

Jan 1, 1993

By Doug Anderson

Two quantities, Peak Particle Velocity (PPV) and Scaled Distance (SD), have controlled aspects of many blasting projects and operations for a long time. Vibration criteria typically use both PPV and SD because they are simple to measure, and simple to calculate. Their use in regulations worldwide is fairly ubiquitous, in efforts to limit damage to structures in the neighborhood of a blasting operation. PPV and SD are also used to determine likely blast damage effects in mining operations.

Jan 1, 2018