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By G Alan Foster

Many complaints generated from blasting operations result from the marked human response to ground transmitted vibrations and air blast effects and so many authorities have considered the regulation of blasting in terms of human response rather than, as previously, in terms of preventing damage to structures.

Jan 1, 1981

By Dale S. Preece, J Paul Tidman, Stephen H. Chung

A discrete element computer program named DMC_BLAST (Distinct Motion Code) has been under development since 1987 for modeling rock blasting (Preece & Taylor, 1989). This program employs explicit time integration and uses spherical or cylindrical elements that are represented as circles in two dimensions (2-D). DMC_BLAST calculations compare favorably with data from actual bench blasts (Preece et al, 1993).

Jan 1, 1998

By Kurt B. Oakes, Brian M. Fortelka

Unimin Corporation operates an underground Silica Sand mine at Guion, AR located in North Central Arkansas. The Silica Sand deposit at Guion is part of the St. Peter Sandstone Formation, which is overlain by a competent dolomitic limestone from the Joachim formation, acting as the roof directly above. Both the St. Peter and the Joachirn Formations are of Middle Ordovician age.

Jan 1, 1999

By Walter Jr Duke

The security of explosive materials is a vital concern to every mine, quarry and contractor engaged in blasting. Proper construction of magazines and sufficient locking mechanisms are the fundamental means of maintaining secure storage. The object of this paper is to review the proper methods of construction of storage facilities for explosives as defined by the Alcohol, Tobacco, and Firearms regulations. Subpart K subsection 55.208 and the Institute of Makers of Explosives recommendations.

Jan 1, 1991

By J R. "Dick" Daniel

Over the past several years, the Hercules Technical Service Group for the Explosives Department has produced a series of programs for the TI59 programmable calculator dealing with explosive application problems. These programs have been made available to both our internal staff and to the Hercules explosives distributor organization. Several of these programs have found good acceptance and wide usage.

Jan 1, 1984

By Conny Sjoberg, Finn Ouchterlony, Bjorn Jonsson

This contribution reports an investigation of the blasting damage in the contour of an access ramp to a Swedish underground laboratory for nuclear waste related studies. Near zone vibration measurements were made for 7 rounds and the results converted to a site specific scaling law. A simple engineering correction for the influence of the charge length wee developed and the resulting equations used to predict the damage zone depths of three different drilling and charging patterns.

Jan 1, 1993

By Paul Worsey, Matthew K. Coy

New blasting mat designs are currently tested in the field on actual blasting jobs and only undergo qualitative rather than quantitative assessment. The majority of matted blasting occurs in trenching in which the blast designs and field conditions vary considerably. In order to assess a new blasting mat material and design, a new standard test was devised.

Jan 1, 2015

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 Paul E. Thompson

Current magazine regulations are designed to avoid injury or property damage caused by accidental detonation as well as to store explosives securely. The primary emphasis appears to be the avoidance of unintended detonation or in the event such detonation occurs, the avoidance of damage to surrounding property. Adherence to these regulations largely serves the purpose intended but has caused difficulty in magazine sitting in built up areas. To the extent that magazine siting is too heavily restricted, other more significant dangers such as storage of explosives in more dangerous and less secure places may be encouraged. In summary, the regulations have served rural magazine locations well but may need further study for urban settings.

Jan 1, 1990

By Scott Gustfason, Richard N. Snyder

What is a safe stand-off distance? Recent mishaps using conventional blasting equipment have seen flyrock as distant as 3,750 feet from the blast area, or close to three-quarters of a mile, therefore, whether below ground, under water, in surface quarries or at a structural demolition site, data signals riding a radio wave promise a new horizon for the users of both electric and non electric blasting circuits.

Jan 1, 1987

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

"Recently, an effort was made to calibrate the Riedel-Hiermaier-Thoma (RHT) material model to reproducethe behavior of granite under impact and explosive loading conditions. The study concluded that the materialmodel captured the phenomenon of compressional damage in granite due to such loading conditionsfairly well. The present work uses hydrodynamic modeling with the calibrated RHT model to estimate thefines generated around a blasthole. This can improve the calibration of different size-distribution empiricalmodels and enhance the prediction of fines."

Jan 1, 2012

By Sergio Segovia Parra, Victor Hernan Sheen Uriol

This contribution of the concept of mass blasting both closing and production allows breaking paradigms, to limit the number of tons to thunder. The areas of geotechnical different mining large mining companies worldwide and especially from the National Copper Corporation (CODELCO, Chile) has been declining volumes closing blasting and production, with the misconception to protect the end walls of the pit, before any geotechnical risks caused by various types of faults; especially the circular faults. A blasting of small tonnage can do more damage to a wall when it is not properly sequenced, leading to the coupling of the wave train and therefore the exponential damage in/s (peak particle velocity, PPV) on the wall of the Tagus. Blasting closing mass production and contribute technically and operationally in the dynamics of the following operations: loading, hauling, crushing, processing and preparation of the final product; eliminating delays to return to thunder small volumes where one must stop all mine equipment, incurring high costs and especially losing valuable time in the continuity of the following unit activities.

Jan 1, 2015

By Florian Bauer

The Fording River mine in British Columbia produces hard coking coal in an open pit operation. Coal seams are exposed by blasting overburden and digging blasted muck with rope shovels. The drilling and blasting process presents a considerable cost factor to the operation. Reducing the amount of explosives needed therefore contributes considerably to costs saving initiatives. However, reducing the powder factor only makes sense if the subsequent loading processes by the shovels are not compromised in terms of productivity.

Jan 1, 2014

BLASPA is the name for a computer code which can assist in the rapid optimisation of blasting procedures in an open-pit mine. BLASPA is based on a mathematical model of the blasting process, a model which has been developing since 1963 as a result of blasting research carried out at the College Militaire Royal de Saint-Jean under sponsorship of the Defence Research Board, and in co-operation with the mining and explosives industry. The model presently includes the following aspects: (1) Geometry, i.e. spacing, burden, bench height, collar, sub-grade drilling; (2) Explosives, i.e. types and grades of explosives, distribution into bottom and top load or decking, size of hole and coupling; (3) Hookup, i.e. parallel or angled firing, delays, location of primers. Computer costs are very small, by comparison with purely spherical AEC codes, so that any number of simulations can be carried out very efficiently. The system has already been used to carry out thousands of simulations for over 40 mines in Canada and abroad. It will be explained how such simulations become a useful guide for a mine's blasting engineer who wishes to optimize his blasting and drilling costs.

Jan 1, 1980

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 Peter Moser

The average annual consumption of raw minerals in Europe is 10 ton per person. About 50 % is produced by blasting. For a population of 450 million (including the population from the countries of the new member states) this makes 2.25 billion tons of blasted rock, 80 % being building industry aggregates and industrial minerals. In aggregate quarries 10-15 % of the rock blasted can’t be sold, as the material is too fine, i.e. smaller than 4 mm. This ‘fines problem’ is worse in the quarries of limestone and cement producers where up to 30 % of the material is useless. Thus about 450 million tons of useless rock fines are produced and put on waste dumps every year, i.e. 1 ton/person. This problem is addressed by the research project LESS FINES - “Less Fines production in aggregate and industrial minerals industry” which is funded by the European Union under the project contract G1RD-CT-2000-00438. The project consortium, formed of nine partners from 5 EU countries, works on the following two main research subjects: 1. The determination of the natural breakage behavior (NBC) of the rock mass, which is defined as the particle size distribution curve for a certain rock mass with the maximum uniformity and thus for a given maximum particle size that fragmentation curve which gives the minimum amount of unusable fine material. The comparison between the NBC and an actual blast fragmentation curve allows to quantify the fines reduction potential. 2. The adaptation of explosives properties, charging techniques and timing in order to produce only the minimum, inherently unavoidable percentage of fines. With about 15 full time working persons the project is estimated to be one of the largest blast related research activities in Europe at the time of the project period. The project is coordinated by the Department of Mining Engineering& Mineral Economics of the University of Leoben.

Jan 1, 2004

By Jonathan Zimmerling, Rob Alkins

The model of waves emanating from a blast hole proposed by Heelan, and further developed by Blair and Minchinton, provides an approximation of particle motion in an isotropic, continuous and homogenous medium caused by a cylindrical pressure source. Previous work in the literature shows that the shapes of the peak strain and peak particle velocity contours generated by this model are influenced by priming location. This paper presents the results of experimental investigations into the effects of priming position in an explosive column and the resulting shape of the surrounding stress and particle velocity fields. Fifteen emulsion charges were detonated in a limestone quarry, of which eight were bottom primed and seven top primed. The charges were fully confined, with no breakout to any surface. Particle velocity was monitored using tri-axial sensors coupled to the rock using cement, and pressure sensors were placed in water filled boreholes for fourteen of the experiments. Statistically significant differences in peak pressure for bottom and top primed shots were observed. Blair and Minchinton developed two pressure source functions, one of which is scaled using the charge weight scaling law. New models of the explosive pressure source are developed and compared to those found in the literature. These models are directly calibrated by predicting the peak velocities achieved at the known locations of the velocity sensors, then minimizing the residual sum of squares between the predicted and observed peak vibration values. Due to the complexity of the model the residual sum of squares cannot be minimized using standard non-linear optimization techniques, so a stochastic, agent based global optimization method is employed. Models are then cross validated by comparing the relative predicted differences in stress between bottom and top priming position to the observed differences.

Jan 1, 2013

By Gungor Tuncer, Ali Kahriman, Umit Ozer, Abdul Karadogan, Mehmet Aksoy, Ertugrul Kaya, Deniz Adiguzel

This research was performed on the quarry that will be opened to produce aggregates and rock filling material at Catalagzi region at Zonguldak providence. Excavations will be done by drilling and blasting. However, there are some structures which can be adversely affected by blasting at the quarry. These structures are a methane exploration drill hole and a house at the distances of 340 m and 390 m, respectively. The one of the main goals of this study is to perform a preliminary assessment of possible damage effect of ground vibrations induced by blasting on these structures by risk analysis based on ground vibration measurements.

Jan 1, 2009

By Tristan Worsey, Nathan Rouse, Daykin Schnell

The authors were retained by a proposed underground metals mine operation to evaluate the potential blast vibration amplitudes that could be generated at surface structures above the proposed mine. Literature reviews of published blasting documentation gave little information, data, or models on surface blast vibrations produced by underground mines. At the client’s request, the authors contacted a number of underground mining operations to evaluate interest in sharing blast vibration data with the authors so that the authors could develop an underground-to-surface blast vibration regression equation. The authors worked with three underground metals mining operations to collect surface blast vibration data produced by heading blasts and stope blasts. The data included blast vibration amplitude values, seismograph records, blast design geometry, charge weights, and detonator delay and sequence designs. The total amount of information was used to produce a regression equation and summary dataset that could be used by the proposed underground mining operation to evaluate blast vibration amplitudes that will be generated on the surface. This work is published and presented so that operations with proposed underground mines or proposed underground mine extensions can use these equations to predict vibration amplitudes on the surface above the mine workings before any blasting occurs.